This is probably the 5th time I have heard a similar discovery story- they are getting so common-regardless of real or not-there is something fishy going on-maybe a theft cover up, tax dodge, etc.
Please see this earlier thread (from the specific Beatles section of this site) where the item was discussed as it was being sold. The price quoted in the article must have been including buyer's premium.
How's this? A new young member bought a Rolls Royce engine hood signed by McCartney (a 13-inch autograph), Bono, Beyonce and many other artists for MTV for £250: