This is the latest in a series of blows to the force, which last week arrested four of its officers in connection with allegations of perverting the court of justice.

North Yorkshire Police has investigated changing its organisational culture after an earlier sexual discrimination case.

Overlooked

Former North Yorkshire Police Chief Inspector Lyn Smith, 46, claimed sexual discrimination because she said she was continually overlooked for promotion during her 25-year career.

She left the force in March on the grounds of stress.

North Yorkshire Police said out of the 18 complaints made, an industrial tribunal in Leeds made three findings of discrimination.

A hearing to decide compensation will be held in Leeds on 13 January.

Rumours

At a hearing in October, Ms Smith said she was nearly driven to suicide over rumours within the force that she was a lesbian.

She claimed senior officers and the then Chief Constable David Burke were among those circulating the rumours.

Ms Smith said she became the victim of slurs after splitting up with her husband - also a police officer - in 1988 when she sought help from her friend, Chief Inspector Christine Hobster, the senior woman in the force.

Ms Smith had been told the force could not sustain her and her husband, David Short, beyond the rank of sergeant - putting irreversible strain on the marriage.

But when the couple broke up, she saw Mr Short promoted through the ranks to chief inspector.

Not promoted

The first matter the tribunal ruled was discrimination related to a decision not to promote Ms Smith in 1991.

But the tribunal did acknowledge the complaint was inadmissible because it was out of time.

Ms Smith claimed male colleagues qualified as a chief inspector when she had failed, even though she had more experience.

She eventually qualified as a chief inspector.

The second ruling of discrimination covered a decision in 1997 when Ms Smith claimed she was overlooked for promotion as a superintendent - despite having more experience than the man who got the job, she said.

The third ruling related to a senior officers' dinner when a sexist comedian was booked and Ms Smith felt she had been embarrassed and had to leave the room.

Conspiracy

After becoming an acting superintendent in Selby, she was criticised by Mr Burke for not leaving adequate cover while on holiday with Ms Hobster.

On her return, Ms Smith was signed off for two weeks due to stress.

Ms Smith became convinced a conspiracy was in place among senior officers, including Mr Burke, to stop her gaining promotion.

In October last year she decided not to apply for a superintendent's job because she feared Mr Burke would be on the interview panel and would refuse to promote her.

She left work in November 1997 and was again signed off due to stress, never to return.

Ms Smith now runs a guesthouse in Scotland with Ms Hobster, who retired from the force through illness in 1994.

'Bright future'

A North Yorkshire Police spokesman said the force regretted the claim had gone to an industrial tribunal.

A statement read: "We fought the case because we strongly believed that we had not been guilty of discrimination. The force management saw a bright future for Lyn Smith and regrets that she left the force."

Adding that North Yorkshire Police had recently introduced a new promotion policy, the statement said the force" will be looking to see what lessons can be learned".

Ms Smith said of the tribunal decision: "I find no pleasure in the fact that I needed to bring this case to an industrial tribunal to achieve fairness in the workplace but I hope the effect will be a positive one."