According to Bob Lonkhurst's bio on Welsh heavyweight Jack Petersen, his first fight with Walter Neusel, dated Febraury 4th 1935, was held at Empire Pool in London, not Wembley Stadium.
The attendance was 11,600.
Also, Petersen's fights with Dick Power, Charlie Smith and Hans Schonrath were all held in the venue called Greyfriars Hall in Cardiff.
They are only listed as Cardiff on his Petersen's record at the moment.
Jack Peterson's record - http://www.boxrec.com/list_bouts.php?hu ... &cat=boxer