On 13 November 2009, Bostock joined League One outfit Brentford on loan for a month, he was handed the number 17 shirt immediately. Bostock scored twice on his debut against Millwall. After an impressive spell in league 1 at Brentford he was given the chance to play at Championship level with Hull City in August 2010.
Hull City FC
Bostock scored with a 30-yard strike described as a “wonder goal” on his debut against Swansea on 7 August immediately endearing him to the Hull City faithful. John nearly bettered his first goal with another cracking strike against Leeds United in the Yorkshire derby with a thunderbolt free kick from 30-yards. He returned to Spurs in December 2010.
Sheffield Wednesday FC
In January 2012 Bostock joined Sheffield Wednesday on loan for the remainder of the 2011–12 season. He made his debut the following day as a substitute in a 1–1 draw with MK Dons. He was recalled to Spurs in March due to a lack of playing opportunity.
Swindon Town FC
Bostock joined Swindon Town on loan on 22 March 2012 for the remainder of the season, after Tottenham manager Harry Redknapp said it would be good for him to play under Paolo Di Canio. He made his debut on 25 March in the 2012 Football League Trophy Final, which Swindon lost 2–0 to Chesterfield. He made his league debut against Gillingham on 21 April. He made his home debut on 28 April, in a 5–0 win against Port Vale in a game that saw Swindon crowned League Two champions. John then made his final appearance on the final day of the season in a 0–0 draw against Bradford.
John returned on loan to Swindon on 30 August 2012 until January 2013. He made his first appearance 2 days later against Preston and made his home debut on 5 September in the Football League Trophy against rivals Oxford United. After much appreciation from the Swindon fans Bostock returned to Tottenham on 7 January 2013.
In February 2013 Bostock trained with two different MLS clubs with a view to a loan move. He officially joined Toronto FC on 8 March 2013, and made his debut for the team the following day. Bostock made a skilful run into the box being brought down and was awarded a penalty which led to a 2–1 home victory over Sporting Kansas City. John gained invaluable experience playing in the MLS and later returned to Spurs to see out the remainder of his contract.
"Going out on loan was a great experience for me, theres been ups and downs but I can certainly say each loan has helped mould me into the player I am today."