Tesco Bank has turned to Allen & Overy for advice on its latest multibillion-pound sale – an unexpected move given the company’s close ties to Magic Circle rival Freshfields Bruckhaus Deringer.

The bank – wholly owned by supermarket giant Tesco – is looking to offload its mortgage unit to Lloyds Banking Group in a £3.7 billion deal, with A&O advising the sellers according to a person with knowledge of the deal. A second person said Freshfields was not involved.