Watford striker Britt Assombalonga has joined Peterborough United in a permanent deal.

Assombalonga has signed for Peterborough for an undisclosed fee but the Hornets have first option to re-sign the striker.

The 20-year-old has signed a four-year contract with The Posh who stated Watford were "reluctant" to allow the transfer.

Assombalonga made two starts and two substitute appearances for the Hornets during the 2011/12 campaign before he spent last season on loan at Southend United, where he scored 16 goals in 49 appearances for the League Two club.

Assombalonga's rise into professional football was very different to most.

At the age of 16, the forward decided to enrol at Hertswood School where he considered doing, among other subjects, law. It wasn't until he arrived that he learned about a scheme with Watford's community trust, which combined education and playing football.

Assombalonga, who can play out wide as well as his favoured position of striker, progressed through the various trials to secure a spot on the team and his performances led to a recommendation to Watford, who offered him a trial.

After being given a scholarship with the club, he impressed for the Under-18s and Reserves and was handed a professional contract by the Hornets in 2011.

The likeable youngster first made his mark at senior level when he scored 11 goals in 15 appearances on loan at Ryman Premier side Wealdstone during the 2011/12 season, which led to a temporary move to Braintree Town of the Conference, where he scored five goals in as many games.

This led to him being recalled by Sean Dyche and Assombalonga's debut in 2012 marked a significant landmark for Watford as the forward became the 50th Academy player to make his first team debut for the Hornets since the Academy was created in 1998.

Peterborough chairman Darragh McAnthony says the Posh smashed the club's transfer record to sign Assombalonga.