A SEX offender has been warned to expect a substantial prison sentence after he admitted attempting to engage in sexual activity in the presence of what he thought was a 13-year-old girl.

Burnley Crown Court heard how Matthew Stuart Harper also attempted to cause the ‘child’, who he thought was a girl called Emma but was actually a police officer, watch a sexual act.

Harper, 39, of Clayton Way, Clayton-le-Moors, committed the offences between March 13 and March 28.

In total he pleaded guilty to one count of attempting to engage in sexual communication with a child, two counts of attempting to cause a child to watch a sexual act, two counts of attempting to incite a child to engage in sexual activity and one count of attempting to engage in sexual activity in the presence of a child.

But he pleaded not guilty to four further allegations of attempting to cause a child to watch a sexual act.

Prosecutor Lisa Worsley said those pleas were acceptable to the Crown and they would not be seeking a trial.

Harper was given conditional bail while a pre-sentence report is prepared.

Judge Simon Medland QC said: “The fact that you are on bail and a pre-sentence report is being ordered should not be an indication of sentence. On June 8 you must expect an immediate and substantial custodial sentence to be passed on you.”