Image copyright Durham Police Image caption (top, l-r) Richard Sheridan, Michael Hegarty, Richard O'Brien Jnr, John O'Brien, Daniel O'Brien, Donald Chi Chong Wong, Alan Clarke; (bottom, l-r) Patrick Clarke, John O'Brien, Daniel Flynn, Ashley Dad, Paul Pammen, Robert Gilbert-Smith, Terence McNamara

The final six members of a gang have been jailed for masterminding the theft of artefacts worth up to £57m from museums and an auction house.

Chinese jade and rhino horn were targeted in Cambridge, Durham, Norwich and Lewes, East Sussex.

The 14 men, from across England and Northern Ireland, were convicted of conspiracy to steal between November 2011 and April 2012.

They were jailed for between 15 months and six years, eight months.

How police caught up with the £57m theft masterminds

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The members of the organised crime gang, from Cambridgeshire, Essex, London, the West Midlands and Belfast were found guilty by jury after a series of trials at Birmingham Crown Court.

They were involved in organising two thefts and an attempted theft at Durham University Oriental Museum as well as further incidents at Gorringes Auction House in Lewes, Norwich Castle Museum and the Fitzwilliam Museum in Cambridge.

Jurors heard exhibits stolen in Durham and Cambridge were valued at about £17m but detectives believed they could have fetched up to £57m on the "booming" Chinese auction market.

Image copyright Fitzwilliam Museum Image caption Chinese artefacts worth up to £15m were stolen from Cambridge's Fitzwilliam Museum in April 2012

The six sentenced on Tuesday were:

John "Kerry" O'Brien Junior, 26, of Orchard Drive, Smithy Fen, Cottenham, Cambridgeshire was jailed for six years and six months

Michael Hegarty, 43, also of Smithy Fen, was sentenced to six years and six months

Richard Sheridan, 47, of Water Lane, Smithy Fen in Cambridgeshire, was jailed for five years and six months

Terence McNamara, 46, of Marquis Street, Belfast, was sentenced to four years

Ashley Dad, 35, of Crowther Road, Wolverhampton - who is currently on the run from police - was sentenced in his absence to five years and three months

Patrick Clarke, 34, of Melbourne Road, Newham, London, was jailed for five years and six months

A further seven members of the gang were jailed on Monday:

Danny Flynn, 45, of Orchard Drive, Smithy Fen, Cottenham, Cambridgeshire was jailed for four years

Paul Pammen, 49, of Alton Gardens, Southend, Essex, was sentenced to five and a half years

Donald Chi Chong Wong, 56, of Clapham Common South Side, London, was jailed for five and a half years

Daniel "Turkey" O'Brien, 45, from Smithy Fen, Cottenham, was given six years and eight months

Richard "Kerry" O'Brien Junior, 31, of Dale Farm, Oak Lane, Billericay, Essex, was sentenced to five and a half years in prison

Alan Clarke, 37, of Melbourne Road, Newham, London, was jailed for five and a half years

John "Cash" O'Brien, 68, of Fifth Avenue, Wolverhampton was given five years and three months

A 14th gang member, Robert Gilbert-Smith, 27, of no fixed address, pleaded guilty on 10 March 2015 and was sentenced to 15 months in jail on 27 April 2015.

Hapless thieves: a catalogue of errors

Image copyright Durham Police Image caption A jade bowl and porcelain figurine were taken in the Durham raid

The gang hit the jackpot when their hired burglars made off with jade valued at about £15m from Cambridge's Fitzwilliam Museum, but before that not everything went to plan:

When you implicate yourself - Computers seized by police showed gang members searching for news about a rhino horn cup stolen in Durham sometime after November 2011. But the theft was never made public, proving to investigators the gang knew something about it

- Computers seized by police showed gang members searching for news about a rhino horn cup stolen in Durham sometime after November 2011. But the theft was never made public, proving to investigators the gang knew something about it When a rhino head is heavier than you think - Realising they could not remove the horn from a rhino head at Norwich Castle Museum on 20 February 2012, thieves decided to carry the entire head across the room in full view of the public. It proved too heavy, and when tackled by staff they dropped it and ran

- Realising they could not remove the horn from a rhino head at Norwich Castle Museum on 20 February 2012, thieves decided to carry the entire head across the room in full view of the public. It proved too heavy, and when tackled by staff they dropped it and ran When you get away with the wrong thing - Thieves intent on stealing a rhino horn libation cup from a Lewes auction house on 16 March 2012 accidentally picked up a cup made of bamboo - worth a fraction of the price. They were tackled by the public and the cup returned

- Thieves intent on stealing a rhino horn libation cup from a Lewes auction house on 16 March 2012 accidentally picked up a cup made of bamboo - worth a fraction of the price. They were tackled by the public and the cup returned When you get the right things but forget where you've hidden them - Thieves hid two items worth £2m on scrubland after stealing them from Durham on 5 April 2012. They forgot exactly where. Gang members spent several days scouring the area before police recovered the artefacts a week later

- Thieves hid two items worth £2m on scrubland after stealing them from Durham on 5 April 2012. They forgot exactly where. Gang members spent several days scouring the area before police recovered the artefacts a week later When you get thirsty on the job - Even the Fitzwilliam jade gang made mistakes. One of them was seen on CCTV on 13 April 2012 throwing a water bottle into a bush as he entered the museum. His DNA later linked him to the Durham raid a week earlier

Det Supt Adrian Green, from Durham Constabulary, who led a four-year covert investigation to bring the gang to justice, said the case had been "like putting together a huge jigsaw with no picture to go on".

Image caption Many of those jailed were detained following a series of raids as part of a multi-force operation on 10 September 2013

"Because of the complexity we were only able to get a conspiracy to steal and that's capped at seven years, which is a bit of a shame."

Some of the sentences were fairly short compared to the seven, eight or nine-year sentences handed to some of those who carried out the burglaries, he said.

"I'm just really pleased that we've been able to bring them to justice."