Yappy, probably a reference to 252 Squadron RAF
"Formed on 1 May 1918 at Tynemouth by amalgamating the ex-RNAS 495, 507, 508, 509 and 510 Flights. It was equipped with Sopwith Baby, Kangaroos and DH6s, the first two being given up in August 1918 and the third being retained until January 1919. These were operated as detachments at Cramlington, Seaton Carew and Redcar. Reduced to cadre in January 1919, the squadron moved to Killingholme where it disbanded on 30 June"
Quoted from:
http://216.239.59.104/search?q=cache...ient=firefox-a
N.R. just means 'Number'
Bletchley