Here you will find links to various web sites with philatelic content as well as references to printed publications I have found useful in my research.

Web Sites

Societies and Institutions

The Royal Philatelic Society (RPSL), the oldest philatelic society in the world also have a separate web site with an invaluable searchable Catalogue of society material.  The catalogue is fully searchable for RPSL members but there is also a limited search facility for non-members - with further details available on the site.

The Great Britain Philatelic Society (GBPS) is a must for any serious GB collector.

The National Philatelic Society (NPS) is one of the largest general philatelic societies in Great Britain.

The Wimbledon and District Philatelic Society is a small, friendly society serving South West London.

The Perfin Society, formed in 1957 with the aim of recording all perfins found on GB stamps, is a must for any GB Perfin collector.

The British Library, Philatelic Collections is an invaluable resource.  Today, some fifty important collections and archives, comprising over eight million items, are held for research and exhibition.

Dealers

As a predominantly GB collector I would recommend the following dealers web sites:

Bill Barrell Ltd  Extensive stock of GB stamps and postal history material.  Fully searchable web site making it very easy to locate items of interest.  Always has something for the overprint/underprint collector.  Bill also has a companion web site Bill Barrell Books specifically for philatelic books.

Andrew G Lager  Specialising in GB stamps, penny black, seahorses, 1d black, 2d blue, postal history etc.

Mulready Philatelics  Specialising in the line-engraved stamps of Queen Victoria, Mulreadies and Pictorial Envelopes.

Samwells  Extensive stock of GB Postal History.  Fully searchable once registered (which is a straightforward process).

Andrew Vaughan Philatelics  Extensive stock available on a web site updated regularly with a monthly list available by post and/or email.

General Philatelic Sites

The most useful philatelic link I have found is Joseph Luft's Philatelic Resources on the Web.  Sites are categorised so you can search on such things as "Collectors Pages", "Country Specific", "Shows and Societies" etc.  A very large number of links, frequently updated.  Well worth book marking and visiting regularly.

The Story about the SPIFS and PERFINs is an excellent introduction to Perfins.  The author has given permission to anyone to download the article for personal use.

is a useful and free philatelic reference link site.

Publications

The primary source of published information on the Protective Overprints and Underprints is Appendix 2 of Stanley Gibbons Great Britain Specialised Stamp Catalogue Volume 1: Queen Victoria (Edition 16 - December 2011 being the current issue at the time of writing).  If you are a serious collector of G.B. Victoria material you will no doubt have a copy of this publication already. 

The Tomkins Catalogue of Identified G.B. Perfins (10th edition) lists all known perfins (as of 2004) on G.B. postage stamps with identified users.  No illustrations are given, which keeps the number of pages down, but a detailed description is given (including a pin count) to allow cross checking with your own specimens.  The catalogue is printed on A4 paper, comes shrink wrapped (as it is unbound) and will fit comfortably into a single A4 binder.  This catalogue is available from The Perfin Society.

The Perfin Society's New Illustrated Catalogue of Great British Perfins is very much a work in progress.  This is a catalogue which, when completed, will list all perfins found on G.B. postage stamps (believed to be well over 20,000).  Illustrations are provided for each perfin along with any known information such as identity, dates of use, the stamps on which the perfin has been found, etc.  This catalogue is being issued a letter at a time.  Each section is printed on A4 paper and comes shrink wrapped (as it is unbound).  I have a copy of all the published sections which just about squeeze into three A4 Lever Arch files.  This catalogue is available from The Perfin Society.