Senior clerk Phillip Lyon, whose job it was to arrange the weekly Prime Minister's Question Time for Tony Blair, was arrested after vice detectives raided his Commons office.

Lyon, 37 at the time, was accused of making indecent images of children. He was also charged with using his home computer to collect more than 1,000 images of children. Some of these images showed toddlers subjected to 'disgusting" sexual acts. He faced 12 counts of making indecent images of children between October the 10^th 2001 and April the 17^th 2003.

The 37-year-old, who wore a navy blue single-breasted suit for a five-minute plea and directions hearing at London's Southwark crown court, stood with his hands clasped in front of him as he entered not guilty pleas to each allegation.

The charge carries a maximum sentence of 10 years imprisonment.

Judge James Wadsworth QC, told Mr Lyon, of Langdon Hill, Basildon, Essex, that his five-day trial would start on March the 24^th 2004. "Your bail is extended until then." he added.

Mr Lyon was arrested in April of 2003 after a raid on his Commons office by detectives from the Metropolitan police vice obscene publications and internet unit.

His main duties were arranging question time on Wednesday afternoons. He had daily contact with senior backbench MPs and sat in on private sessions of the select committees as they cross-examine witnesses.

He was discovered by chance when an IT consultant came to repair another clerk's computer at the Commons and opened a file named 'something terribly wrong', London's Southwark Crown Court was told.

Riel Karmy-Jones, prosecuting, told the jury Lyon had used his computer "to pursue his interest and perhaps curiosity in this type of material." She said "He searched for it on the internet and when found, downloaded it for his delectation later."

"He had far wider usage of the internet than these 12 occasions." said Ms Karmy-Jones.

In court, Lyon denied he could have downloaded pornography at work, because other people had access to his computer and anyone could walk into his busy, open office. He also said others had access to his computer.

When arrested, Lyon allegedly likened his problem to that of a drug addict. "It is like a drug – you try one and you want to try something harder and it has a snowball effect." he told officers.

Found guilty on all charges Lyon was sentenced to for one year in prison.