The College's collection of coins is housed at the Fitzwilliam Museum (see below). The following few items remain in the College Library.

Contemporary forgery of Edward I penny
Silver, 18mm, worn. Obv. Crowned bust of king, facing front Leg. EDWAR ANGL DNS HYB. Rev. Long cross, three pellets in each quarter Leg. CIVITAS LONDON.
In envelope labelled 'Contemporary forgery of penny of Edward I/III (these were known as 'lushbournes', since John of Luxemburg was their chief perpetrator)'.

Contemporary forgery of Edward III penny
Silver, 15mm, very worn. Obv. Crowned bust, facing front. Rev. Long cross, three pellets in each quarter.
In envelope labelled 'Contemporary forgery of penny of Edward I/III (these were known as 'lushbournes', since John of Luxemburg was their chief perpetrator)'.

Charles I rose farthing
Copper, 13mm, worn. Obv. Pair of crossed sceptres passing through crown Leg. CARO: D:G: MAG: BRI: Rev. Rose surmounted by crown Leg. FRA. ET. HI. REX.

Charles II farthing
Copper, 21mm, worn. Obv. Bust of Charles, l. Leg. CAROLVS A CAROLO. Rev. Britannia Leg. BRITANNIA.

George I farthing 1724
23mm, very worn. Obv. Bust of George, r. Leg. GEORGIVS REX. Rev. Britannia and date 1724 Leg. BRITANNIA.

Napoleon III 5 centimes 1853
25mm, worn. Obv. Bust of Napoleon, l., and date 1853 Leg. NAPOLEON III EMPEREUR. Rev. Eagle Leg. EMPIRE FRANCAIS CINQ CENTIMES.

1. 18th-century farthing. 28mm, too worn to be identified.
2. 18th-century halfpenny. 22mm, too worn to be identified.
3. Two 18th-century tokens. 25mm; 22cm. In envelope labelled '1 German & 1 French 18th century tokens'.

Two pound coin commemorating the bicentenary of the act for the abolition of the slave trade 1807
28mm. Obv. Bust of Queen Elizabeth II, r. Leg. ELIZABETH. II. D. G. REG. FID. DEF. TWO POUNDS. Rev. 1807, with the 0 being a broken link in a chain Leg. AN ACT FOR THE ABOLITION OF THE SLAVE TRADE 2007. Edge. AM I NOT A MAN AND A BROTHER.
Six coins given by Dr Robin Glasscock, Nov. 2007. Two coins transferred from the College Archives, May 2014.

A history of the College's coin collections

In his diary of a visit to Cambridge in 1710, Zacharias Konrad von Uffenbach records that he saw a cabinet of coins in the library of St John's College: 'We were shewn the cabinet of coins, which scarcely deserves the name. For it is poor in itself, and contains but little, so that there is nothing specially to be reported of it. I must however make mention of one gold nummi of Arcadio, which is very fine. On the one side is his face: DN. ARCADIUS P. F. Aug. In aversa figura he is stans, una manu vexillum cum monogrammate, altera Victoriolam globo insistentem tenens, pede vero hominem prostratum calcans, with this inscription: VICTORIA AUGG. Below CONOB. and in the centre on either side of the figurae stantis M.D. There were in all about eight gold coins.' (J.E.B. Mayor, Cambridge under Queen Anne (Cambridge, 1911) p.176).

This modest collection expanded enormously following the donation of over 1200 Greek, Roman, English and continental coins to the College by a Mr Bromsall in 1758. This donation is recorded in a letter from the Master of the College, John Newcome, to John Orlebar of the Middle Temple (printed in The Orlebar Chronicles 1553-1733 (London, 1930) p.60).

I have received the Box, in which the medals, urns and other curiosities, given by Mr Bromsall, were inclosed and being put into a strong case, are come safe to hand. We return you our thanks, and will send an authentic catalogue, when made out, with a Discharge to the Executor.
I am, Sir, for myself and College,
Your obliged humble Servant,
J. Newcome.

March 26, 1758
We shall lodge them in proper new Drawers and make honourable mention of our Benefactor.

Despite Newcome's pledges, Mr Bromsall's identity has not been preserved for posterity, and no catalogue of the collection appears to survive.

In 1885, W.E. Heitland sought the Library Committee's permission 'to take in hand the formation of a College Coin Collection for the Library' (Library Committee Minutes 11 Dec. 1885), and in 1887 placed a number of his own coins and medals in the Library 'in the hope that they may form the nucleus of a College collection' (The Eagle XIV (1887), 122). Further donations followed later that year: a number of Roman Imperial silver coins from Miss M.L. Mayers, a gold Rose-noble of Richard II from Mr Haskins (ibid., 189), and other coins from Mr Cox, Mr Ward, Messrs Pendlebury, H.S. Foxwell, Brill, Stapley, and A. Macalister jun. (ibid., 251, 409). Heitland hoped to arrange and catalogue the collection but his wish does not appear to have been realised, and in 1889 he removed his own coins from the collection (Library Committee Minutes 7 Dec. 1889). In 1901 the Revd W.G. Searle rearranged part of the collection, and reported to the Library Committee on 'the unclassified coins remaining in the two cabinets' (ibid. 14 Feb. and 30 Apr. 1901). The following year Mr Rapson examined the collection, and it is clear that at this time the gold coins were displayed in a glass case. Rapson offered to make a selection of historically interesting coins from 'the Large Cabinet' which might be displayed in an additional glass case, but this plan does not appear to have been taken up (ibid. 13 Feb. 1902).

In 1937 the College Council agreed to deposit the Library's collection of coins at the Fitzwilliam Museum, 'record being made of the name of the original donor, Mr Bromsall' (CM 1529/9 14 May 1937), and the following year the coins were duly transferred on permanent loan, although any medals of College interest were retained (Library Committee Minutes 2 Mar. 1938).

The following extract from a letter from the Fitzwilliam Museum, dated 20 July 1939, makes it clear just how large the College's collection of coins had become: 'The report of the Syndics says that this College deposited two collections, one "The Bromsall Collection 1758" consisting of 1235 coins (Greek, Roman, English and Continental) and two terra-cotta plaques, the other consisting of 1265 coins (Greek, Roman, English, Continental and Oriental) with some medals. How the Museum decided what was the Bromsall Collection I cannot say; we had no accurate record of Mr Bromsall's gift here. We were just as ill-informed about the donors of the rest of the coins etc., but the following are known to have given coins to the College: A. Freeman, J.T. Ward, E.C. Ratcliff, A. Macalister, A.M. Stapley, J. Brill, H.S. Foxwell and W.E. Heitland.'