We are a company within a group.

3 years ago due to substantial fuel increases our manager (who runs our company) increased our mileage rate from 15p to 20p.

18 months ago with fuel prices soaring, some team members indicated that effectively they were out of pocket driving there own car on employers business. Our manager heard that HMRC rates were paid within other group companies and authorised this change.

Neither of the above decisions affected him personally at the time as he drove a company vehicle.

The group MD is now challenging this decision as it didn’t go through the board and is talking about reducing the rate back to 15p. These rates have been paid to staff for the last 3 years (first rate) 18 months (higher rate).

What is legality of this ie can they reduce the mileage rate so tha employees are out of pocket? Also the manager made the decision based on belief that he had every right to make that decision as the overall manager of the company.