The British Library Philatelic Collections is the national philatelic collection of the United Kingdom with over 8 million items from around the world. It was established in 1891 as part of the British Museum Library, later to become the British Library, with the collection of Thomas Tapling. In addition to bequests and continuing donations, the library received consistent deposits by the Crown Agency and has become a primary research collection for British Empire and international history. The collections contain a wide range of artefacts in addition to postage stamps, from newspaper stamps to a press used to print the first British postage stamps.

The first notable philatelic donation was in 1890 by Hubert Haes of two albums of postage stamps collected by himself and Walter Van Noorden. It was donated with the request that the British Museum library (now the British Library) would create a philatelic collection.

The following year the collections were established with the bequest of the Tapling Collection. The probate value of the Tapling Collection was set at £12,000 but on arrival Richard Garnett (Assistant Keeper of Printed Books) estimated their value at more than £50,000 and described the bequest as the most valuable gift since the Grenville Library in 1847.

In 1900 the Crown Agents for the Colonies sent three albums of postage stamps made on their order for colonial governments and then sent specimens of all future stamps commissioned.

In 1913, the Crawford Library was received which forms the cornerstone of the British Library's philatelic literature collection, containing about 4,500 works. The Crawford Library was donated by the Earl of Crawford in his Will and was the foremost collection of philatelic books in the world at the time.

In 1944 Mrs A. Cunningham donated her father's collection (Edward Mosely) of African stamps and in 1949 Mrs. Clement Williams donated her late brother's collection (H. L'Estrange Ewen) of railway letter stamps, valued at £10,000. After being offered in 1942 but delayed due to the collections being in secure war storage, in 1951 it was announced that Mrs Augustine Fitzgerald had donated an extensive air mail collection. The Mosely and Fitzgerald collections were valued at the time at £30,000.

The Department of Printed Books had been in charge of the Philatelic Collections by default rather than design. In 1936 there was an unsuccessful proposal to move the collections to the Department of Prints and Drawings and in 1946 there was a further proposal for the Department of Coins and Medals to take charge. No decision could be agreed and Printed Books continued to manage the collections until they were passed to the newly formed British Library in 1973.

From 1948, H. R. Holmes had been the curator but in the late 1950s had wished to relinquish the post. A replacement curator was not easily found and the care of the Collections was managed on a part-time basis. A security crisis in 1959 developed after it was discovered that the contents of one of the frames in the Tapling Collection was missing. In 1961 James A. Mackay was recruited as a research assistant to take care of the Collections. In 1971 the police arrested Mackay (promoted to Assistant Keeper in 1965) and charged him with stealing items from the British Museum Philatelic Collections on loan from the Crown Agents. The stolen progressive proofs (test prints of stamp designs) should have been returned to the Crown Agents for destruction and were valued at £7,600. Mackay had exchanged the proofs for Winston Churchill stamps worth £400. He was fined £1,000 and dismissed from the Museum. As a result of the thefts, security was improved by recruiting Bob Schoolley-West, one of the investigating police officers. The Crown Agents withdrew their agreement for lending new stamps for display in the King's Library.