Have withdrawn question as answered

Thanks for the advice, now closing as didn’t realise needed to edit the email address but find I can’t delete it!

I’m confused
Are you saying you still have a six week deposit from the original tenancy and did not change it in accordance with TFA?

No, because the tenancy is an old continuous one and the deposit did not therefore require to be changed as we understood from the new regulations.

For all new tenancies the deposit is five weeks only

Many thanks for your advice.

My Tenancy Began Before 1st June 2019 and the Deposit is More than Five Weeks’ Rent: Do I Need to Return the Excess Amount?

No, not unless you renew the tenancy. If the tenancy lapses into a periodic tenancy, then this is not a ‘new tenancy’ as defined in the Act.
Tenant Fees Act (2019): What Landlords & Tenants Need to Know | OpenRent Landlord Hub.
If you renew the tenancy, however, then yes; you will need to make sure any tenancy deposit does not exceed the maximum amount of five weeks’ rent.

You can do this by returning the excess to the tenant. Here is how to return excess deposit amounts to a tenant.