PC Joan Moore and PC Geoffrey Robinson of the British Transport Police came across Gary Bryant, 35, at the station at about 11pm on June 23.

Peter Hussey, prosecuting at Chester Crown Court, said: "The officers saw the defendant acting a little suspiciously as he was walking across from the overbridge.

"They went to speak to him and they suspected that he might be in possession of drugs."

Mr Hussey told the court they found a golf ball-sized plastic bag containing a hard substance.

Further analysis revealed it was crack cocaine thought to be worth about £1,400.

Mr Hussey said: "There was 14g of cocaine with a purity of 78 per cent.

"He (Bryant) is a drug addict and owed money to a dealer in Anglesey.

"The dealer asked him to recompensate the debt by going to Liverpool to collect the drugs and deliver them to Anglesey."

Bryant, of Llanerchymedd, Anglesey, admitted possessing crack cocaine with intent to supply.

He was sentenced to four years in prison minus 68 days spent in custody.

Andrew Green, defending, said Bryant had a longstanding addiction to class A drugs.

He said: "In 2000 he moved to Anglesey and started a new life with his partner and they had three children.

"To hold down family life and stay away from the courts gave him resolve and determination.

"It's sad that he has slipped back."

The Recorder of Chester, Judge Elgan Edwards, issued a crown court commendation to PC Moore and PC Robinson.

He said: "I'm impressed by the conduct of the British Transport Police who spotted something was amiss.

"As a result of their actions it has prevented a sizeable amount of drugs getting to the public."