The Royal Air Force Museum has been ordered to pay more than £48,000 to a former member of staff it unfairly dismissed.
Employment judge Jane McNeill said the charity put Colin Reilly in a "pistol-to-the-head" situation by asking him to resign or accept a "radically different" new role.
In tribunal papers published last week after a two-day hearing in Watford in March, the judge ruled the charity's claim that it had offered Reilly a similar role, which would have reduced his annual earnings from between £37,000 and £38,000 to £25,000, "verged on the far-fetched".
She added: "The unilateral imposition of a new contract on the claimant at a significantly lower rate of pay was repudiatory and the failure to operate a fair consultation process, with a 'take-it-or-leave-it' approach, was a breach of the mutual term of trust and confidence."
Reilly joined the charity, which operates RAF museums in Cosford, Shropshire and Colindale, London, in 1994.
He had been employed as a controller, with responsibility for on-site safety through jobs such as monitoring CCTV and dealing with alarms, for 18 years.
In February 2016 the charity, which had an income of £17.2m in the year ending 31 March 2017 and employs 172 staff, told him controller jobs were being deleted and new "visitor experience supervisor" roles created as part of a reorganisation.
The VES roles, which a charity document said would help to create "a positive visitor experience", involved more dealing with customers and some tasks Reilly was not used to.
But according to the papers he "was told he was expected to slot into the VES position".
Reilly claimed the new role was a demotion.
He wrote to the organisation saying he had not been found a "suitable alternative" and was being made "effectively redundant".
The judge found that Reilly's job was deleted and he was told to accept the alternative job or resign. "There was what has been graphically described in Hogg v Dover College as a ‘pistol-to-the-head’ situation," she said.
"The VES job was radically different from the controller job. The suggestion by the respondent that the VES was a largely similar role to the controller job verged on the far-fetched.
"I concluded, looking objectively at all the circumstances, that the claimant’s old contract was withdrawn from him and radically different terms of employment were imposed on him. That constituted a dismissal."
The tribunal ordered a basic award of £10,298 for unfair dismissal and a compensatory award of £37,743 for loss of pension.
A spokesman for the museum said it would not be appealing the employment tribunal’s decision.
"The museum sought and followed independent professional advice with regard to the suitability of the alternative role offered to the claimant during the formal consultation process," he said.