Stephenson Harwood has won victory in the Court of Appeal for members of BT's pension scheme, blocking the telecoms giant from changing how it calculates payouts.

The firm successfully argued that the company cannot change the way it calculates interest rate increases to certain categories of its pension scheme – which would have seen about 80,000 beneficiaries affected. 

Stephenson Harwood's team was led by pensions partner Helena Berman.

BT had sought a High Court ruling last year regarding its aim to change the index used to calculate pension increases on one category of its pension scheme, which could have seen the company switch from the typically higher retail price index to the consumer price index.

The court rejected BT's case, following which the company appealed the decision at the Court of Appeal.

CMS acted for BT. The firm currently sits on the company's legal panel, having successfully retained its place last year alongside 36 other firms. 

The BT Pension Scheme Trustees, who worked alongside BT in its challenge, were represented by Slaughter and May. The firm fielded a team led by regular BT pensions scheme adviser Sandeep Maudgil and disputes partner Richard Jeens.

Last year, Slaughters advised on the UK's largest-ever pension scheme restructuring, which saw Tata Steel offload its £15bn British Steel Pension Scheme.

BT said: "BT is considering the judgment in detail in order to decide next steps, and the trustee will provide further updates as appropriate."