Bought this oddity yesterday. Its a Rattlesnake and the sticker says made for IDL-Distrib-Tenderden West Germany to BS6102
Serial number on the rear drop out says 1 (or could be a j) 3450 (looks like a backwards c) 991

Shame the BMX seat has a chunk missing..

Stem is a Win cr-mo BMX product of Japan

Brake levers are MX Polygon with Weinmann calipers

Forks are Tange TX-500 cr-mo steel forks

Unusual bottom gusset

Twin top tube, the padset had been sewn on!!

Rear drop outs and o.s pegs

Coaster tab

GT seat post, seat post clamp is a Japan SR

Cranks are Takagi crmo 175 x 24, I couldn't get a good pic of them.
Anyone ever seen anything like it?