LONDON — The practice of office workers pitching in to buy a gift for a departing colleague — especially one with decades of service — is an old tradition.

But when staff members at the Tate Modern and Tate Britain art galleries in London were asked this week to contribute to buy a gift for the Tate group’s departing director, many raised eyebrows over the present: a sailboat.

The timing was awkward. The call for contributions came as the Tate group, which operates four museums and art galleries across the country, was in pay negotiations with staff.

The situation highlighted concerns over widening inequality in Britain before a general election in June. As in other Western countries, questions have been raised over the concentration of the benefits of economic growth with the elite, as employee rights have eroded and wages have flatlined.

In the case of the Tate, a letter was posted in staff rooms asking for donations toward a going-away present for Nicholas Serota, the group’s director since 1988.

“We have thought long and hard about what to get, and decided to put money towards a sailing boat,” the note, photos of which were posted on Twitter, said. “Nick loves sailing, and this would be a lasting and very special reminder of the high regard which I know so many of us have for Nick and his contribution to Tate.”

Pay negotiations have been tense. One trade union claimed that even after wage increases proposed by the museum group, staff pay would range from 15,707 pounds to 23,695 pounds, or about $20,230 to $30,520. By contrast, Mr. Serota made almost £200,000 in 2016-17, a Tate spokesman said.

Trade unions and workers’ rights advocates also complain that some people working at the Tate group’s museums via outside contracting companies are subject to so-called zero-hours contracts, in which their employers do not guarantee a minimum amount of work a week. As a result, these workers do not have dependable income.

At the Tate Modern art gallery, along the River Thames in London, two employees, who declined to give their names but wore Tate uniforms and identification lanyards, said workers had initially thought the request for donations was a joke.

To mock the letter, one said, workers made a paper boat and affixed it to the note.

“This shows how far Tate management are removed from the reality of the everyday lives of Tate staff and the fact that many of them can barely afford to pay their bills,” the Public and Commercial Services Union, which represents workers at the group, said by email.

“It is insensitive that Tate management would even think to do this and we would encourage them to concentrate on listening to our concerns as we campaign for fair pay, more staff and an end to outsourcing at Tate.”

Tate, which operates the Tate Modern and Tate Britain in London, and Tate St Ives and Tate Liverpool, said in a statement that the idea for the gift “came from the staff themselves who wanted to mark his 28 years of service to Tate.”

“Contributions towards the purchase of a small dinghy, which the staff thought would be an original gift, are entirely voluntary.”

A spokesman for the Tate group declined to elaborate on which staff members had proposed the idea and did not disclose how much money had been raised. But, in an emailed response to questions, he said, “Tate has reiterated to staff today that any contributions towards the gift are entirely voluntary and has apologised if the way the proposal was communicated was insensitive.”