A BNP Paribas executive is suing the French bank for £3.9m, claiming she was subjected to a campaign of bullying and harassment by male colleagues that included having a witch’s hat placed on her desk.

Stacey Macken, a development manager in the bank’s prime brokerage division in London, alleged at an employment tribunal that she was forced to work in a “toxic” and “laddish” environment and was paid less than her male peers.