With immediate effect Royal Mail have made their Postmark Bulletin available as a free pdf download.
Published every 2 weeks, the Bulletin can be found at royalmail.com/postmarkbulletin
We will continue to include some special handstamps here on our blog, and on our website on individual stamp issue pages, but if our pages are not updated then collectors and dealers should refer to the online resource.
The Bulletin also includes addresses of Royal Mail's regional philatelic Special Handstamp Centres in London, Edinburgh, Cardiff, Birmingham, and South Shields. In our webpages the handstamp number is preceded by code
E and L for London
M for Birmingham [Midlands]
N for South Shields [North of England]
W for Cardiff [Wales & West]
S for Edinburgh [Scotland & Northern Ireland]
F for British Forces
FD - see details within the Bulletin
Note that postmarks for any individual stamp issue may appear in several successive Bulletins and may even be published after the issue date of the stamps. Operational slogan postmarks are not normally mentioned in the Bulletin.
UPDATE 4 March 2016
Royal Mail have announced that with immediate effect the Postmark Bulletin is free of charge. Existing subscribers will not be charged for renewal when their subscription expires.