Hi Hettie,
Egg is part of Citigroup PLC, but has its own banking licence under Egg Banking PLC.
Cahoot is part of Banco Santander, and operates under Abbey National's banking licence.
Abbey is also part of Banco Santander and operates under its own banking licence. So if you have accounts with Cahoot and Abbey, they are covered under one banking licence.
HSBC operates under its own banking licence.
For more information please check out our guide to who owns who and who has a banking licence.