A prisoner jailed for masterminding a £1m-a-year international prostitution ring here has complained that a “racist” British prison has banned him from flying an Irish tricolour in his cell.

Thomas Carroll was jailed for seven years at Cardiff Crown Court in 2010 after pleading guilty to running a network of 18 brothels in Northern Ireland and the Republic.

The court heard at the time how Carroll, now 50, and his South African wife Shamiela Clark forced up to 70 women to work as prostitutes after they were trafficked into Ireland from Europe, South America and Nigeria.

The pair ran a ‘call centre' from an old vicarage in Wales arranging deals with traffickers, who had told the women they would find work as hairdressers and seamstresses in Ireland.

But when the women arrived, Carroll and Clark sent them to rented apartments in Northern Ireland and the Republic where they were told to wait for clients.

The couple earned around £1m-a-year from their 15 brothels in the Republic and three in Northern Ireland, the court heard.

Now, in a letter from his cell at privately-run HMP Parc, a category-B prison run by G4S in Bridgend, Wales, Carroll has complained that the prison is discriminating against him.

“Upon having a paper flag taken from my cell wall by a Parc employee I requested that my family send a flag in by mail,” Carroll wrote in his letter to prisoners’ newspaper Inside Time.

“But when it (arrived) the authorities refused to let me have it because it constitutes a ‘security issue'.”

Carroll, originally from Bagenalstown, Co Carlow, added: “As a proud nationalist and republican, I deem it to be my right, as it is the right of any of my countrymen and women, to be in possession of our national flag.

“The refusal to allow me my flag is discriminatory and racist.

“I respect the fact that I am in a British prison and would only have displayed my flag in my own cell and not in public view.

“My ancestors fought for the right to fly our national flag and ... I reserve the right to fly the Irish tricolour wherever I may be.”

A spokesman for G4S said that the security firm was investigating the claims.

Belfast Telegraph