Jack played in a trial game at the start of the 2009/10 season at the Cat and Fiddle and St James Park. He was described as “a forward who had been released by West Ham United”

Jack Jeffery who was born in Gravesend on the 13th of August 1989, joined West Ham United in 2004.

In 2007/08 he played regularly at under-18 level and for the reserves. He also played on loan at Hampton and Richmond, where he made 6 appearances and Cambridge United, where he played 10 games, scoring once.

He joined Leyton Orient on loan on the 12 September 2008, making  his league debut the following day, but because of injury he returned to West Ham.  On 2 March 2009, Jack signed on loan for Eastbourne Borough, where he scored 3 goals in 13 matches.

He was not offered a professional contract by West Ham and was released in the Summer of 2009. After his trial with the Grecians, Jack subsequently signed for Grays Athletic. He was released by  Grays in November, after just 4 appearances.
He went on to sign for Maldon Town, Sevenoaks Town.
In August 2011, he signed for Chatham Town, staying for two seasons before moving to Corinthians and later Greenaway. In 2015 he returned to play for Chatham Town.