I've also got a white demo and sold my spare issue copy about six months ago. After having been after a copy for YEARS, I first bought the issue copy for £100, then won the demo copy on eBay in January 2006 for $34. Promptly managed to re-sell the issue copy for £150 so a good deal in the end as I got some money "back". It's an extremely hard record to find and is consistently undervalued.
The flipside "Make Your Move" is very gritty and closer to garage rock than soul in my opinion and might be collected by the garage scene, I don't know. But I rather think that it's genuinely rare and that's why it's so hard to find.
The 70s styrene reissue incorrectly states the title as "You're Number 1" while the original has got it down as "Your Number 1".
Top, top tune.
Scans below of both the issue and demo copies: