A paedophile who escaped checks to teach in at least three Sussex schools has been jailed for four years.

Nigel Gordon Jackson, 48, a former deputy headmaster of Seaford Head Community College, mouthed "sorry" to his victim's parents after he was sentenced at Londonderry Crown Court yesterday.

The court heard that Jackson had broken bail conditions in October last year when he was caught with a 14-year-old girl on Brighton seafront.

Jackson was sacked from Seaford Head for grooming a 14-year-old schoolgirl on the internet in January 2004 but went on to teach in at least three other Sussex schools when a loophole in the law allowed him to get agency work in West Sussex.

He was finally caught and tried in Northern Ireland after using the internet to dupe a Co Derry schoolgirl into thinking he was a 15-year-old boy.

The parents of the Sussex girl say they are pleased with the sentence but shocked Jackson was still able to meet teenage girls while on bail.

The girl's father said: "Unbelievable. Like a drunk I suppose he thought if you're going to jail you might as well get drunk again. They shouldn't be allowed out on bail.

"The sentence is excellent. Now the law has been changed to protect children in the future. That's all we really wanted.

"You expect children to respect a deputy headmaster. He abused his authority."

Jackson, from Bowden Rise, Seaford, East Sussex, had admitted internet grooming at a previous hearing, when he also admitted to two sample charges of inciting a child to commit an act of gross indecency and a charge of indecent assault.

Jackson was sentenced to four years in jail and ordered to not to undertake any work, voluntary or paid, which would bring him into contact with girls under 17.

He was also banned from communicating or attempting to communicate with girls under 17 in any form - electronic, written or oral.

West Sussex County Council has promised to make changes to its procedures to ensure paedophiles do not enter its schools again.

Chief Inspector Tara Nicholl, of the Police Service of Northern Ireland, said: "We are pleased to see the investigation brought to a successful conclusion with the sentencing of Nigel Jackson here today.

"The details of the outcome of this trial will be updated on our own computer systems and shared with the police National Computer - thereby ensuring up-to-date information on Jackson is available to all police services throughout the United Kingdom."