Ah, but it was not your remembered piano recital to which I referred, but Mark’s post-WWII Gabor Cossa silent piano performance.
Dude, I have one!
–Greg-k
P.S. Interesting tidbit of corroboration though from the Tom Roper blog, except that he is back off of something in the entry update–though it is not clear what.
Please note the section that has been marked in bold. i believe we can now see the problem.
I wrote some extensive lyrics that can be sung when playing the stringless piano
Here they are 
GR, I’m not a fiction writer, and I’m afraid to say I’m also of Vic-K’s age. That is indeed Gabor Cossa’s antiques shop in Trumpington Street, but my reference is to a time long before it must have been sold to David Theobald (17 years ago, i.e. around 1990). I was a student at Peterhouse from '64 to '68, at which time the owner of the shop was the eponymous Gabor Cossa, who was into his 60’s at least at the time.
Mark
Edit …
You will also find mention of him and Cambridge at the same time by Sir Ian McKellen in mckellen.com/stage/r2/words.htm
and in
Wow, my post must have been very unclear. I never doubted that Gabor Cossa owned an antique shop just as you said (after all, you say you knew him in that connection). What I was raising a question about was whether he really performed a silent piano piece just after WWII.
When I saw vic-k’s rememberance at the top of this thread, I too thought immediately of John Cage’s piece, but before his name came up, you posted this intriguing historical item. Just the sort of curiosity to attract my attention. When the big Google hits I came up with included 1) the man’s antique shop, and 2) a “Gabor Silent Piano” outfit named after a quite different Gabor,* I started to think someone was having a laugh here. Maybe it was you (this proved false), or just maybe Gabor Cossa was having you on back in the day. Who knew?
So, in short, I didn’t think to doubt your story about the guy you knew. Just wondered if the story the guy told you was true.
–Greg
P.S. In round two, I also found record of some archived, music-related correspondence from a Gabor Cossa in 1943-46 at which time it seems he was writing on behalf of an outfit called the Ballet Jooss.
Greg,
according to Ian McKellan, Cossar used to be a dancer:
mckellen.com/stage/r2/words.htm
from Mark`s link above:
Same guy?? Looks like old Gabor led a very eventful life!!
Take care
Vic
Yep, same guy … a wacky character.
Mark
I saw this production early on its run. Along with Edward II which McKellen did with the same company a couple of years later, it was one of the great performances.
And of many distinctive touches which he brought to the part, his gliding entrance (almost as if he was on castors), was one of the most distinctive. It immediately told you a great deal about this king.
Interesting to discover where the idea originated.
Coincidentally, and completely unrelatedly, I seem to remember at around the same time a novel being published and sold with - yes - entirely blank pages. I suppose the idea was that readers could find whatever they wanted in it. 
This being the 60s, there was a lot of stuff like that about. But I can’t discover any reference on Google.
I remember a punk band that released a cassette tape (album on tape) that the B side was Blank. The reason was during that time there was talk from the record companies wishing to ban Blank Tapes because they felt the public was “stealing music” when they made mixed tapes or tapes for friends. When this band Heard about this they fit the whole album on Side A of a 45 min tape and left the B side blank and the little Tab at the top still there so you could use their album to make your mixed tape on the backside.
45 Minutes of sold silence for you use to use how you wished . 