Robert MacBryde, who had been attaching labels to the back of pictures in an adjacent room, came rushing through and cradled Colquhoun's head as his partner of almost 30 years took his last breath.
This fatal heart attack had been a long time coming. Both Colquhoun and MacBryde, the so-called Golden Boys of Bond Street, worked hard and partied hard, and had been at the epicentre of bohemian London life throughout the 1940s and 1950s.
Bad news travels fast, and in his home town of Kilmarnock, which Colquhoun hadn't visited since 1946, news of his premature death quickly reached his old school, Kilmarnock Academy. Artist Davy Brown remembers the moment well.
"I was just 12 and had only just started at the school. I was in the art room and I remember my art teacher, Jock McKissock, looking shocked and saying, 'Bobby Colquhoun's dead!' I didn't really know who he was talking about, but he told us Colquhoun was someone he'd known when they were both at Glasgow School of Art in the 1930s."
Brown learned Colquhoun had also been a star pupil at Kilmarnock Academy in the late 1920s and early 1930s. Not long after, pictures of his work started appearing around the picture rail in Room E8. Then, when he was 14, Brown and his classmates were taken by McKissock to see a travelling Scottish Arts Council exhibition over the road from the school at the Dick Institute in Kilmarnock.
"There was a Colquhoun in it called Woman With Cat," Brown recalls. "It was an amazing piece of work and I remember thinking 'I want to do that'."
Fast forward to 1980, and I am a pupil of Brown's at Kilmarnock Academy and studying for an O-Grade in art. Around the walls of Room E8 are strange-looking reproductions of paintings and prints which Brown has pinned up. They are of higgledy-piggledy people, animals and still lifes, and they all have a vivid black line, whether they are coloured or monochrome. All recognisable, yet seemingly breaking the rules of drawing we are learning about it for our exam. The figures seemed tortured to my young untrained eye.
Soon, I'm looking at Colquhoun paintings and prints in my lunch break over the road at the Dick. The memory of the work is indelibly etched on my mind.
Today, to celebrate the 100th anniversary of his birth in the Ayrshire town, a new exhibition of Robert Colquhoun's work opens at the Dick Institute. I'll be one of the first in line to see it. As will Brown, who has spent the best part of 30 years collecting the work of the Ayrshire men known simply as The Two Roberts and acting as a champion now that most of the people who knew them are gone.
This exhibition precedes a major celebration in November of the work of The Two Roberts at the Scottish National Gallery of Modern Art. A selling exhibition is planned to take place around the same time at The Scottish Gallery, also in Edinburgh.
Brown, himself a highly collectable painter, is lending around 50 works to the SNGMA exhibition. He has also loaned several works to the Dick, including what is thought to be Colquhoun's last work. The monotype, Astronaut, depicting an astronaut who dies in space, was completed shortly before Colquhoun's death in the Bloomsbury gallery.
The Dick Institute show also includes work from Colquhoun's early career, including pieces he made at school, and works by MacBryde, who came from nearby Maybole. Also on show is work by some of the artists who were contemporaries and influences on The Two Roberts, including William Scott, William Johnstone, John Minton and Graham Sutherland.
This exhibition - and the ones in Edinburgh featuring both men's work - will hopefully signal a resurgence in interest for The Two Roberts, whose work was feted way beyond the small towns in Ayrshire where they were born and raised. In 1948, the curator of New York's Museum of Modern Art bought work in London which summed up the new wave of British artists known as the Neo-Romantics. He chose just five works; by Francis Bacon, Edward Burra, Lucian Freud, Robert Colquhoun and Robert MacBryde.
At the moment, there is no permanent recognition of Colquhoun's legacy in his home town, although various attempts have been made in the past to mark his connection to the town. In 1972, a Robert Colquhoun Memorial Art Gallery opened within the Palace Theatre complex, but this is long gone. There was also an annual Robert Colquhoun competition which ran from 1972 until 1980.
Davy Brown hopes this will change. "It would be good if the centenary of Colquhoun's birth prompted the local authority to put in place a permanent memorial to him in Kilmarnock," he says. "The very least East Ayrshire Council can do is provide a place where people can go and see his work. I'm sure something permanent would draw people to town. There's tourism potential there apart from anything else."
Brown is willing to put his pictures where his mouth is to make this happen. "If the conditions were right, I would happily give a large part of my collection of work by The Two Roberts on a permanent loan."
Now, there is an offer not to be sniffed at. Meanwhile, while there is indeed work on show by Colquhoun in his home town, I urge you to go see it.
Robert Colquhoun 1914-1962, The Dick Institute, Kilmarnock (01563 554300, www.eastayrshireleisure.com) until April 19