A former teacher at Eton College sexually touched pupils during regular "nocturnal visits" while they were alone, a court has heard.

Matthew Mowbray, a 49-year-old father, denies nine counts of sexual activity with a child against four boys and one girl over a period of several years at the elite Windsor boarding school.

He has admitted downloading hundreds of indecent images of children, as well as creating pseudo-images of boys at the prestigious public school by superimposing their faces on to the naked bodies of unknown children obtained online, Reading Crown Court heard.

Mowbray, who appeared at his trial in a suit, has also admitted one count of voyeurism relating to a series of covertly filmed images showing a boy at the elite boarding school getting dressed, jurors heard.

Opening the prosecution case on Wednesday, John Price QC said Mowbray would pay regular "nocturnal visits" to partly-clothed boys while they were alone and his offending spanned a number of years.

Mr Price said the "manual contact" that Mowbray had with the boys was "gratuitous".

He added that the defendant purported "to engage them in conversation about college matters, would touch or stroke them on their arms or, through the bed covers, on their upper legs.

"It is alleged this was done for his own sexual gratification."

Mr Price said Mowbray's alleged offending took place even after he had been warned by a colleague.

The prosecutor said: "If he was prepared to take such risks, with the obvious potential for great harm to his own career and reputation, continuing to do so even in the face of explicit advice from a colleague that he should desist, one is entitled to ask what motivated him to do so?

"Why was it he could not bring himself to stop?"

Mowbray, of Locks Heath, Southampton, was dismissed from his role at the £40,000 per-year school following his arrest.

He is on bail.

Mowbray has admitted six counts of making indecent images of children and one count of voyeurism, jurors heard.

The charges relate to hundreds of indecent pictures found downloaded on to his computer during police investigations, some of which had been digitally altered to include the faces of boys.

Mr Price said: "The prosecution submits that evidence of this activity by Mr Mowbray, proves beyond doubt what was his concealed and true purpose when touching the four boys."

The alleged sexual touching of a female alleged victim "is submitted to make no difference" to the case, said Mr Price, who added: "A propensity sexually to abuse children may often not distinguish between boys and girls."

He told jurors: "That most of those who have complained about Mr Mowbray are boys, may reflect little more than the fact that through his employment he had almost unfettered access to boys of that age, but not so many opportunities to come into contact with young girls."

Eton College was founded in 1440 by Henry VI, and has around 1,300 pupils aged between 13 and 18.

Since 1945, five prime ministers have been educated within its grounds, including Boris Johnson, while Princes William and Harry also undertook studies there.

The trial, before judge Heather Norton QC, continues.