Ordnance Survey special one-inch 7th series map enlarged to 50K in 1970.

Ordnance Survey One-inch map, Sheet 50(M) Forfar. One of eight late Seventh Series maps specially enlarged to 1:50,000 and printed for educational purposes in 1970 with contours relabelled in metric values. These maps were the testbed for the full metric conversion of the series which started four years later. Flat sheet with later folds. Free second class postage within UK. Overseas mailing at additional cost by arrangement.