Professor Robert Donovan, 67, from Midlothian, met Prof Hawking when the pair were at Trinity Hall College, Cambridge, 55 years ago.
Prof Hawking’s son Robert is named after Prof Donovan and the Dalkeith resident’s daughter shares the same name as Prof Hawking’s first wife Jane.
Prof Donovan said: “We were very close and it was a privilege to have known him. It was always interesting to speaking with him. He could be controversial and when I first met him I thought he was eccentric. He taught me so much. He just always had ideas. He was a fascinating guy and was very modest about what he knew. He was a great teacher and loved communicating to people.
“I last spoke to Stephen in December when he invited me to a dinner party and he knew he did not have long to go. I was devastated to hear he was going downhill rapidly.
“Finding out he had passed away was heartbreaking. He was my best friend and I will miss him so much.”
Prof Hawking was the first person Prof Donovan met when he arrived at his new home in Cambridge. He was going to do a PhD in reaction dynamics while Prof Hawking was completing a PhD in singularities.
He said: “We lived in the same late Victorian college house. He could still walk really slowly at this stage.
“I parked outside and rang the door bell. There was no answer so I tried round the back and I saw Stephen Hawking playing croquet. The gamekeeper was out shopping so he invited me to his room, put some music on and he made me a cup of tea. I tasted it and it was terrible. It turned out it was green tea, which was not very common in those days. He would speak to me until two or three in the morning.”
Prof Hawking married twice, first to Jane Wilde in 1965 and then to nurse Elaine Madson in 1995. On both occasions he turned to Prof Donovan to be his best man, with him returning the favour for his marriage.
He said: “It was an honour to be Stephen’s best man. His second marriage to Elaine he was trying to keep a secret. He had a wedding at a registry office and the blessing the next day in church. On the day of the service it was unbelievable. There must have been 50 reporters, photographers and TV cameras there wanting the story. When we got to the reception I mentioned to Stephen that the service the next day would be a nightmare. However he said to me ‘tomorrow, I’ll be yesterday’s news’. And he was right.”
He recalled at least three lectures by Prof Hawking in Edinburgh, the most recent of which was in 2000 in front of a packed McEwan Hall.
Prof Donovan said: “His lectures were mostly pre-recorded with his voice synthesiser. But he knew when to pause to put in a joke or to put in relevant information regarding that area. He would ask me about the football with Hibs and Hearts.”
Prof Donovan moved to Edinburgh in 1970 to take up a lecture role at Edinburgh University, a position Prof Hawking was instrumental in him taking. He became is now a senior honorary professorial fellow.
He said: “I lived with him for two years and the only regret I have from leaving Cambridge was that I had to leave Stephen behind.
“He was a singularity. The universe started with a singularity with the big bang. He was the big bang in my life.”