And the welsh opera singer, bryn terfel. Thick fog is causing delays at airports for a second day. Heathrow says 45 flights have been cancelled, because planes were in the wrong place following yesterdays disruption. And its new year down under, sydney welcomes in 2017 in style with a spectacular firework display. Now on bbc news, witness. Hello, and welcome to witness with me, tanya beckett. Im here at the British Library in london for the last time this year to bring you five of our favourite stories from 2016. Well meet a former member of chairman maos infamous red guards, a woman astronaut who trained with the challenger Space Shuttle crew, and an art restorer who brought a Leonardo Da Vinci masterpiece back to life. But first, witness has travelled to the Bamiyan Valley in afghanistan. For over 1,000 years two huge statues of Buddha Towered over the valley, but in 2001 they were destroyed by the taliban. Said musa hussein was one of the local people forced to lay dynamite around the statues. Said musa hussein, talking to witness in afghanistan. This year is the 50th Anniversary of the start of the Cultural Revolution in china. At the forefront were the red guards, fanatical students determined to help chairman mao eliminate any vestiges of capitalism. Our next witness saul yeung was one of them. Newsreel the biggest nation on earth, china, is in turmoil. Is chinas ageing leader losing control . Has mao gone mad, driven by the megalomania of the teenage red guards . Mao had decided to drive the young people in a vast campaign to purify the communist party. There was to be a new revolution, a Cultural Revolution, a revolution in peoples thinking. Inspired by mao, the red guards went wild in their enthusiasm to keep the revolution alive. They worshipped mao as their leader and followed his instructions without question. They consider long hair and western style clothes uncommunist. After reports of rioting, beatings up and even murder, the red guard seem to have gone too far. Their leaders have told them to cool off and go and help with the harvest. Saul yeung, talking to witness in san francisco. In january 1986 tragedy struck the Us Space Agency nasa, when the Space Shuttle challenger exploded shortly after launch. Six astronauts and a School Teacher were killed. Barbara morgan was another teacher who trained alongside the challenger team. My husband and i, we were sitting on the sofa watching the news, and President Reagan came on and made this announcement, it was quite remarkable. Today i am directing nasa to begin a search and to choose as the First Citizen passenger in the history of our Space Programme one of americas finest, a teacher. Ill always remember my husband, who was a writer, jumped up immediately and said, why a teacher, why not a writer . And i laughed and said i thought a teacher would the perfect choice. Christa was chosen as our teacher in space. I was very, very lucky to be chosen as her back up. Christa was very much like the girl next door. She had an effervescent smile. She was very intelligent and just soaking it all in. Christa spent six months with me training with the challenger crew. Some of the favourite training was with the simulators, to learn what it was like to be weightless. We did not stop laughing that entire flight. Launch date was january 28th. We had been at the Kennedy Space centre for a few days and the crew had been spending time in Crew Quarters going through all the last minute work and preparations for the flight. And that morning it was a very, very cold morning. We of course had School Children all over the country watching. There were, you know, 100 kids from christas sons school there. And all of the families and friends. I remember i was so excited, i so wanted to be with them. I was waving, and i am sure i wasjumping up and down. Really cheering them on, really really happy for them, and wanting to be there with them. We have main engine start, four, three, two, one and lift off. Lift off of the 25th Space Shuttle mission, and it has cleared the tower. Very soon into the launch, things didnt look right. There wasnt one contrail going up, and that looked very different from the launch that christa and i had watched a few months earlier. And then at some point you realise that something has gone terribly wrong. Flight controllers, you are looking very carefully at the situation. Obviously a major malfunction. We all went to Crew Quarters, where we were waiting word, and helping the families. It was, you know, a really tough situation. In september, i went back to the classroom, and i taught for many, many more years. In 1998, many, many years later, nasa asked me to apply for the astronaut office, the astronaut programme. At that point i left teaching, and went and served as an astronaut for ten years. One of the wonderful legacies of the challenger is the Educational Programme that the families of the challenger crew members got together and created, where young people for themselves experience the joy and wonder of space flight and space exploration. It is called the Challenger Centre for Space Science education. That is why the challenger crew were going into space. They were going to explore and discover and experience for all of us, and to keep that future wide open for all of us. Former astronaut Barbara Morgan talking to us at her home in idaho. Remember, you can watch witness every month on the bbc news channel, or you can catch up on all of our films along with more than 1,000 Radio Programmes in our online archive. Now, a story of cold war intrigue and the bbc. In 1978, a bulgarian dissident called Georgi Markov was working in london for bbc world service. On his way into the office he was stabbed with, of all things, a poisoned umbrella. Witness has tracked down dr bernard reilly, who tried to save mr markovs life. I remember walking into the cubicle and Georgi Markov was on the trolley, sitting up. He was hot, toxic, he had a rapid pulse rate and his temperature was up. The first thing he said that, i was warned three months ago that they are out to get me. And i have been poisoned by the kgb and i am going to die and there is nothing you can do about it. Markov was driving to work at the bbc. He parked as usual below waterloo bridge. Markov came up the steps of the bridge, towards the bus stop on the road above. As he reached the bus stop, suddenly something happened to markov. He suddenly felt a sharp stabbing at the back of his right thigh, and he looked around expecting the person behind him to apologise for prodding him with an umbrella. Instead of which the man hailed a taxi. Mr markov finished his shift, and it wasnt until late that night at his home in clapham that he developed high fever. When i examined him systematically, the only thing that i could find was on the back of his thigh he had, perhaps, sort of a Centimetre Diameter swollen area, with then a 1 2 millimetre central puncture mark. I thought, well, i best phone Scotland YardSpecial Branch because they are the sort of people who deal with defectors. His own room at the bbc Bulgarian Service was used by Anti Terrorist squad detectives investigating the murder. I thought it cant be cyanide, that would kill you too quickly. It cant be thallium or arsenic, that is too slow. It had to be a toxin. And if there was a toxin there might be an antidote. So i then went home, and my wife said you should read more agatha christie. And she had just read a book called the house of the lurking death, ricin in the figs. I dont think this was an intuitive diagnosis, it was because of the book she had read at the time, but the odd thing was that she was proven right, it was ricin. His heart had started giving out, and ijust saw the heart machine die away, and shortly after that he died. I had to go to the postmortem. I remember the pathologist taking a segment of thigh tissue where this area was. As this was being handled, a very small metallic object was dislodged. As it sort of rolled onto the table, and they then looked at it under a microscope and realised that it was actually a very round, circular, tiny little ball about, sort of, just under two millimetres in diameter, and that it had holes in it. And obviously something could have been contained in those holes. They decided almost straightaway that this was going to be ricin. It is a poison which is incredibly toxic. It is strange that you encounter one patient so early on in ones career that actually changes your entire life. All i wanted to be was a forensic pathologist. I wanted to be someone who looked at dead bodies, looked at laboratory findings, and decided why people die. And this was the first patient i am trying desperately to keep alive, and failing. And realising that actually i didnt want to find out why people died, i wanted to try and keep them alive. Dr Bernard Riley with that extraordinary story. Finally this month, witness has travelled to milan to meet the woman charged with restoring one of the worlds great masterpieces, Leonardo Da Vincis last supper. Pinin brambilla finished her painstaking work in 1999 after spending 20 years on the project. The last supper was painted here 500 years ago for the refectory of santa maria. But due to his experimental fresco technique, it started to flake away almost as soon as Leonardo Da Vinci had finished it. Now, a mouth on, restoration has attempted to save one of the worlds masterpieces from disappearing completely. By stripping away centuries of botched restoration attempts, lines which were crude and inexpressive are now delicate and refined. The mural is by no means perfect, and some critics feel too much paint has been removed. Pinin brambilla, speaking at her studio in milan. Thats all for witness for this month and this year. We will be back in 2017 with more stories from history, told by the people who were there. From me and the rest of the witness team, goodbye. Hello, the last day of 2016 and its looking cloudy and damp for the majority of the country with limited spells of brightness. Some with limited spells of brightness. Sunshine across 1 pennines. Some sunshine across the east of the pennines. Across scotland and Northern Ireland we are seeing a change. Rain spreading southwards with some much colder air digging in behind bringing some wintry showers. You can see on The Rain Band and the south, relatively mild temperatures between 7 12dc. The all important evening as we had on to new years eve and towards the bells. The wet weather spreading southwards, eventually clearing Northern Ireland and southern scotland. It should be dry and cold for most of us from midnight. Watch out for ice patches developing and wintry showers particularly across the north of scotland. Across the south, the england and wales, itll stay cloudy and damp. Light rain with some low cloud and murk. That rain band pushing towards north wales and towards northern england. Relatively mild, through the night across england and wales. Much colder across the north with strong, cold wind developing. Behind this cold front with some rain, temperatures will be falling away. Spreading across will be falling away. Spreading a cross m ost will be falling away. Spreading across most of the country through the new years day, the first of 2017. It looks like it will be cloudy, are lots of rain around. Maybe wintry showers over the higher ground. We start off on a fairly dry, damp note in the south east. If you spots of rain. In northern england, Northern Ireland and scotla nd england, Northern Ireland and scotland it is a cold, crisp start but with some sunshine. It will be breezy particularly across northern areas. Watch out for ice first thing. Then for the midlands, southern and south eastern parts it will stay wet with heavy bursts at times. A bit of brightness getting to north wales, the far north of england. North of the country will stay bright but very cold with some wintry showers. Then that colder, drier, brighter air moves in across the country for monday. A frosty start with plenty of sunshine around. The england and wales, the best of the sunshine. Scotland and Northern Ireland cloudy. There could be some spots of rain as well. This is bbc news. Im annita mcveigh. The headlines. Australia welcomes in the new year in style with a spectacular of fireworks over the Sydney Harbour bridge. Security is stepped up in major cities around the world and here in the uk for new year crowds and celebrations after the deadly Lorry Attacks in germany and france. Therell be police officers, stewards, there will be a Search Regime in place and people need to give extra time on the day so they can come and have a safe and enjoyable event. Hundreds are honoured in the queens new years honours list including many of britians 0lympic and paralympic stars including mo farah, lee pearson and andy murray. I feel still like andy murray, feels