Canada, Unitrade 36b, Stanley Gibbons 78b, 2c + Bisect on cover to Halifax.  Light strike of PETIT DE GRAT / JY 24 91 / N.S. CDS ties attached Bisect & single to cover, which existed as a post office only from 1866-1894 (then reopened in 1953), addressed to Halifax, Nova Scotia.  Large stains & edge faults, none of which affect either strike of the CDS or the stamps.  Reverse: blue ARICHAT / JY 24 / NS CDS receiver. 

Accompanied by a 1952 RPS Certificate which states genuine, but probably "made for collectors". 

The 2009 Unitrade Specialized Canada Catalogue states that "covers postmarked 'Halifax' are a private speculation".  This cover has a PETIT DE GRAT postmark, so it may or may not be philatelic.  A rare cover either way.  2015 Unitrade Specialized Catalogue of Canadian Stamps CV: $2,750.00 for covers.  2016 Gibbons CV: £2,500.00.