French postmarks collector, I sometimes find english ones.
This unusual (?) one seems to be a London fancy cancel, but I do not find informations about it.
http://cjoint.com/14fe/DBjot77dwwq.htm

This is a newspaper agent pre-cancel, starting inthe 1870's. Issued to
certain large newspapers and agents to pre-cancel them before mailing.
Alcock and Holland are the GB cancel specialists, this is their type
#1590