Tony, I admire your cheek - that's $'000 of consulting you're asking for free!

You might want to look at the sub-typing of Client & Branch:
- is it necessary?
- a buiness-org doesn't have gender, salary, first/last name, dob etc: so why are these attributes on the super-type?
- do single and married clients have different attributes?
- do the London, New-York branches have different attributes? not really according to your diagram, so they don't model well as sub-types.

The sub-typing of Loan looks bizzare to me, but I don't know the business.