Over the past few weeks, the playwright and lecturer Matt Morrison has been clearing out the premises, used by the University of Westminster as a storage space, and adding a lick of paint.
It was a Proustian moment when, with Irving Wardle and Michael Billington, I descended the little staircase, which used to be painted red (a few remnant red flakes of it are still discernible) and entered the low-ceilinged room where Verity Bargate, the late ex-wife of the founding director, Fred Proud, used to stand sentry with crusty bread and hot soup.
Good grief - there was Fred himself, and Verity's brother, and David Edgar, who had two plays put on at the Poly, both of which were later televised (one of them, Baby Love, was given a rehearsed reading to round off the mini-festival last night).
And on the walls, they had pinned up some of our yellowing reviews, and other memorabilia. Billington proclaimed an astounding list of writers whom the Poly had promoted and produced, and Wardle noted how places like the Poly and the other lunchtime theatres of the time - they formed an association in late 1972 - were an essential outlet for new writers as the Royal Court had turned in on itself with its established stable to look after.
The space seemed instantly recognisable and instantly ready for action: how marvellous if Matt, or some enterprising young producer, could re-invent the lunchtime model and mix up a menu of short classics - the Poly used to put on short plays by Shaw, Chekhov, Arrabal, Sheridan and Durrenmatt - with new short plays.
There is a group called the Miniaturists, dedicated to presenting short but perfectly formed new plays, and they put on three 20-minute pieces on Wednesday. The Miniaturists were born in reaction to the Monsterists, who campaign for new plays on large stages. And now, David Edgar told us over lunch in a nearby Sicilian restaurant, there are the Antelopes, an angry bunch who first met in the Antelope pub round the corner from the Royal Court.
I had no idea all this was going on, and it seems to me the various factions really are in dire need of a producer, and someone to open up the Soho Poly again as a dedicated venue; the Soho Theatre, its successor in Dean Street, has its own busy and comedy-oriented agenda.
The early plays at the Poly were highly satirical. The first one I ever reviewed, The Trial of St George by Colin Spencer, was an uproarious parody of the Oz Trial (in which three underground magazine editors were arraigned on an obscenity charge and famously defended by John Mortimer); an innocent suburbanite from Gidea Park in Essex was put in the dock on a manslaughter charge after his wife had dropped dead on catching a glimpse of his penis.
The judge was played by the late, great Nigel Hawthorne, whom I'd seen in repertory in Hornchurch, which is quite near Gidea Park, just a few years earlier. His participation on the burgeoning new fringe was a good indicator of how theatre was changing and shifting away from so many hidebound traditions at this time.
Short plays by Barrie Keeffe and Howard Brenton, as well as by Edgar, Pam Gems, Caryl Churchill and others, reverberated far beyond these tiny confines, where there was seating for just 48 people and a warning to mind your head when you stood up.
But if I had to pick just one short play from that magical period on the fringe, it would be Snoo Wilson's Soul of the White Ant in 1976. Simon Callow played Eugene Marais, a mystical poet, lunatic and naturalist, whose study of termites in South Africa yielded a set of theoretical anthropological writings that were shamelessly filched by the theatrical visionary Maurice Maeterlinck - who won the Nobel Prize in 1926. Marais committed suicide ten years later, bitter and destroyed.
You simply don't see anything of that density and brilliance on the fringe very often, though it was great to catch up with latest developments at the Soho last night when a consortium of writers - including Simon Stephens, Labour MP Chi Onwurrah, the promising Zoe Cooper and comedian Dylan Moran - unveiled their visions of utopia in Utopia.
Unfortunately, this made me yearn for a time warp machine to whisk me back once more to the early 1970s and Fred Proud's bargain basement of unpredictable delights. The link between the two houses continues, however, most markedly when one of Fred and Verity's two sons was recently married on the Soho Theatre mainstage in a civil ceremony. I'd have settled for that instead of last night's banal dreamland of not very clever wishful thinking.