A row over changes to the Boots company pension scheme could end up in the High Court.

The trustee company that manages the scheme has denied accusations of making changes, which could affect thousands of members, in “secret”. Members have complained that they will get a reduced amount if they take their pension before the age of 65. They claim they were told that they could take it in full from age 60.

Phillipa McNamara, a former pharmacist, worked at Boots for 33 years. She fears she may be £2,500 a year worse off because of the changes, unless she delays taking her pension. “The stress is unacceptable. I think the way the pensioners have been dealt with is shocking,” McNamara said while waiting for the result of her second formal complaint.

“We believe experienced and longstanding pharmacist employees of Boots have been treated very shoddily by this secret change,” said Paul Moloney from the Pharmacists Defence Association (PDA), the main union representing pharmacists. “We are aware of people within weeks of retirement who were told they would now get about 80 per cent of the pension they had been expecting.”

Boots Pension Scheme, which has about 53,000 members, is a final-salary scheme that closed to new members in 2010. This type of pension pays a guaranteed income in retirement. It is managed by Boots Pensions Limited, a trustee company.

The changes were made in November as part of a £4.8 billion buy-in deal with the insurer Legal & General, which agreed to take over the pension scheme’s liabilities. Boots pension scheme has bought an annuity policy from L&G and will use the income to pay members their final-salary pension. The pension scheme said the deal will provide a “gold standard” of security for members’ benefits and Boots provided £670 million of funding.

The Boots pension scheme said the changes had been clearly communicated to its members when it wrote to them about the L&G deal in November. The letter said staff would still be able to take their pension at 60, but would no longer be able to do so on the full amount.

It said the right to take a full pension from 60 was always discretionary — meaning trustees could decide whether to allow early retirement on a case-by-case basis. It said that trustees had agreed that pensions would be reduced if members accessed them before age 65.

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Former employees say they had always believed they had the right to retire at 60, however. McNamara, 58, left Boots in 2018 and decided to take her pension early when she was made redundant from a job last year. She was expecting £20,000 a year but after the changes she has been told she will get only £17,486 unless she waits another five years.

Paperwork sent by Boots to McNamara in 2003 said her contractual retirement date was when she turned 60, and in 2010 she was sent forecasts based on being allowed to take 100 per cent of her pension then. “I never had any cause to question it,” she said.

She complained to Boots in December and was told her contractual retirement age was different to the normal age for the scheme. She made a second-stage complaint in April but is yet to hear back. “Every day I am waiting for the post,” McNamara said. “The anxiety you feel when you are waiting for something that could be life-changing is unacceptable.”

Last month, the trustees of the pension scheme wrote to some members to say it had signed a deed of amendment, which changed its rules on the same day the deal was signed with L&G. The amendment scrapped the clause allowing members to take a full pension at age 60 if trustees agreed. Women who built up pension benefits before October 1994 and men who built up benefits between May 1990 and October 1994 will not have this part of their pension reduced if they choose to retire at 60.

The scheme had made transitional arrangements so that members who had been issued with an early retirement quotation within six months of the deal being agreed could retire on those terms. McNamara will not benefit because her most recent quotation was issued on May 22 last year — two days before the cut off.

Moloney said: “We are astonished that despite our request for the disclosure of all papers relating to the scheme rules, this amendment was not disclosed and was kept secret.”

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The PDA has written to the pensions regulator, the pensions ombudsman, and the Boots pension scheme. In a letter to the trustees it said a High Court judgment could determine whether the change has been made within the pension scheme rules.

The PDA has asked the regulator if the Boots pension scheme broke the law by failing to tell it about the deed of amendment when it requested information about the rules, including amendments, in January. It said the scheme could be fined £50,000.

The ombudsman, which can award compensation, said that because of the number of people potentially affected it would take a “lead case” approach. Typically this means that one case is singled out and accelerated through its decision process and the same outcome is then applied to similar cases.

A spokesperson for the pension scheme said: “The buy-in transaction with L&G secured the Boots scheme members’ benefits with a leading insurer … All existing benefit entitlements continue to be provided and changes to discretionary practice were communicated. The company and the trustees firmly believe this transaction was in the best interest of the whole membership.”

L&G said: “Changes to the discretionary benefits are not made by L&G. This is a decision made by the trustee of the scheme, having consulted with Boots and taken legal and professional advice. L&G has no input over the rules of the scheme.”