Woodrups was my local shop between 1975 and 1984. S M Woodrup sounds like Steve, son of Maurice the proprietor. Steve was the primary frame builder in those days, but seldom advertised the fact on a frame- they were all "Woodrup" branded.

The business would build bikes to customer order but did not sell their own frames as complete bikes, as a general rule. Most of their business came from local racers and club riders. Leeds rivals Bob Jackson Cycles were more renowned for exporting to the states and catering to tourists. Unusual to see a Woodrup with extra under-tube bosses or rack brazings. Not unheard of- they did something similar for me in 1981;-)

Chances are your frame has cast lugs to complement the top quality bottom bracket shell. It deserves a pampered life, with better components and a single colour, enamel paint job...........