biscuits, I found this on our Documents check list for proof of residence:-
If you are married to, or in a civil partnership with, a British citizen, you must have been in the UK for the past 3 years.
If you are not married, or in a civil partnership with, a British citizen, you must have been in the UK for the past 5 years.
If you are an EEA National, you need to include letters from employers, educational establishments or other government departments, indicating your presence in the UK during the relevant 3- or 5-year period.
If you are a Non-EEA National, you need to include your passport to prove you have lived in the UK for the relevant 3- or 5-year period.
If you do not have your passport or it was not stamped when you entered the UK, you need to include letters (for example, from your employer or government department) as proof.
Bank statements or household bills are not suitable proof you have been living in the UK.
Do you think just the passport showing initial entry and the current passport will be enough?