Basic sales grid, U.K. ([Overprinted on] Ordnance Survey of Northern Ireland. The Quarter Inch Map, second edition.
[London :  Institute of Marketing, 
1971]
From; Basic Sales Grid - U.K. Revised 1971-71 edition. Reseach and compilation by E.B. Groves.
Great Britain is separately covered on two sheets, Scale 1:625,000.
Vol. placed in X.221.e.