Numbers

help.what is it and how old? the photo copied log book says first registered in 1951 as 40 manx. aluminium engine & barrel is stamped 4726(the head is much larger than the barrel& is square with6 fins at the rear) the frame should be the same according to the log book.the frame is rigid , and stamped 40 61697.is this a 1935-6 frame but what from?the gear box is stamped1-1-21-1-1.77-2.97 no kick start.is it 1935

thanks for any info ian