A curiosity:

The Ontario Government produced perfins at Ontario House, its office in London, England. The office, opened in 1908 by Mr. N. B. Colcock, remained in operation at 163-164 Strand until 1934. During this time it has been reported on the following stamp issues: SG 267, SG 322, SG 327, SG337, SG 342, SG 357, SG 362, SG 367, and SG 368. Dated postmarks are known from 18 May 1912 to 22 June 1921.