Companies in the UK and Europe have pointed to HSBC, BNP Paribas, Citigroup and Barclays as the best banks for advising them on issues related to the Brexit vote – guidance that corporate clients say too few financial firms are providing.

Business consultancy Greenwich Associates asked about 120 treasury professionals at UK and European companies which banks were offering them the best trade ideas and solutions on the UK's referendum on European Union membership, once before the June 23 vote and once after.