Nicola Lamb refused to answer questions

The 49-year-old blonde, dressed in a bottle-green shirt and a knee-length grey skirt, smiled throughout the 30-minute conference but refused to answer any questions.

Mr Kenworthy said: "We have made tremendous changes in the way that we view diversity within the force.

"We celebrate diversity in North Yorkshire police. We are happy to employ people who will be good police officers and support staff."

It came to light during a recent tribunal involving West Yorkshire police that North Yorkshire was employing a transsexual officer, said Mr Kenworthy.

North Yorkshire Police took the decision to hold the news conference at the force headquarters at Northallerton because it is believed a Sunday newspaper was set to "expose" Miss Lamb.

She has wrestled with this transition for a number of years

Kathy Anderson, North Yorkshire Police

Mr Kenworthy said: "Due to press interest this week, I think that it is prudent to deal with this and to be quite open about my, and the force's, attitude to transsexual officers.

Miss Lamb, who has no children, now works in the communications department, helping set-up the installation of a new radio system.

Kathy Anderson, North Yorkshire Police's diversity advisor, said Miss Lamb was "extremely brave".

She said: "Everyone has been very supportive - there has been no discrimination.

Positive reaction

"She has wrestled with this transition for a number of years. Nicola is a lot happier now."

Miss Lamb had returned to work this week wearing women's clothing for the first time.

It has been agreed that she will wear civilian clothes for a month before she comes to work in a female uniform.

Nicola Lamb: "Extremely brave"

Mr Kenworthy said he believed the public reaction would be a "positive" one.

"Most members of the public expect police officers to be a police officer.

"As long as that individual is professional, then gender is not an issue.

"We want the best people working for us and will do everything we can to support them in their work.

"The police service reflects society. I am really pleased that Nicola has done this today.

Employment tribunal

"In the past we have been criticised for our attitudes. Now we are positively leading the way."

Earlier this month an employment tribunal was told that Essex and North Yorkshire police forces were employing transsexual officers.

The claim was made at an appeal where West Yorkshire police were trying to overturn an earlier ruling in favour of a transsexual who has been trying for five years to join the force.

Stephanie Harrison, representing the woman in her 30s, known only as A, told the hearing: "Since the decision of the employment tribunal police forces are actively recruiting transsexuals."

But West Yorkshire police is seeking an authoritative ruling from the tribunal as to whether A is legally still a man, which it says would present an "insuperable obstacle" to her carrying out searches involving more than removal of a female suspect's outer garments.