The "Dodo-Postcards" watermark is NOT on the actual card – it is an online watermark only.
National Maritime Museum. Old Royal Observatory. 24 hour gate clock. E. Baylis. England. No. 252
Greenwich. National Maritime Museum. Old Royal Observatory. Artisan Press. England. No. 239
24 hour gate clock. Old Royal Observatory. National Maritime Museum. Her Majestys Stationery Office by E. Baylis. 1976
24 hour gate clock. Old Royal Observatory. National Maritime Museum. Card No. 252. Albion Printers
Greenwich Planetarium. Old Royal Observatory. National Maritime Museum. Greenwich. Card No. 231. W. S. Cowell
The Time Ball Signal. Old Royal Observatory. National Maritime Museum. The Artisan Press
Greenwich. The Old Royal Observatory. National Maritime Museum. Larkfield Printing
