Members of the group used sledgehammers to smash the store’s windows before grabbing a large number of high value watches.
On Thursday 28 October, Gibbon was jailed for two years and nine months after admitting burglary other than in a dwelling.
Knox was jailed for three years and 10 months after also admitting burglary other than in a dwelling.
Detective Constable Paul Beasley said: “This was a pre-planned and targeted burglary where the suspects ended up stealing £247,000 worth of jewellery.
“Three men were arrested at the scene, but what followed was an extensive investigation by detectives who managed to track down two others involved in the crime.
“I’m delighted with the result and I hope this reassures local businesses that we take crimes like this very seriously and investigate all available lines of enquiry to identify those responsible and bring them to justice.”