First recorded in my registered label database without stamp :

The cover re emerged on eBay with an inscription related to the stamp being missing? (wierd - possibly just an image representation), at a listed £30 it was clearly not done to extract a large amount of money - but clearly shows there are people out there willing to doctor philaletic items and shows a reasonable attempt at a faked cancel - or a genuine cancel and stamp aligned to match.

This was listed with other similar envelopes which may well have been through the same process?