Gotta hand it to BikeExif, truly interesting material there!
Paraphrased from them: Yellow Peril is one of three sprint bikes were built by a cabinet maker called Bill Bragg, who first took up circuit racing in the mid 50s with a Triumph sidecar outfit. The yellow fairing is a fiberglass fuel tank from a P51 Mustang fighter; a trick used by several ‘Lake Racers’ in the US but another first for the UK. 'Yellow Peril' ran the quarter mile in 13.39 seconds.
Photos and words via BikeExif