1851 Toronto to Sandwich, Advertised, bridges transition.

1851 Toronto (MR 22) to Sandwich, UC, bs (MR 25), ms rated “1 1/2″d collect.. The letter was not delivered and ms “Advertised & not called for / not known”, and returned with new Sandwich, UC hs (JY 5 1851). Reverse with London, UC transit bs and red wax “Canada Crown Lands” with crown seal.

This cover is rather special in that it was mailed under British control (up to April 1, 1851) and returned during the period of Canadian control (after April 1, 1851).