The difficult bit will be finding the NI number from 35 years ago.
Eligibility
Plan your retirement income: step by step - GOV.UK
"If you live or work abroad (or have previously)
To pay Class 2 or Class 3 voluntary contributions you must have either:
Eligibility
Plan your retirement income: step by step - GOV.UK
"If you live or work abroad (or have previously)
To pay Class 2 or Class 3 voluntary contributions you must have either:
- previously lived in the UK for 3 years in a row
- paid contributions or had Class 2 contributions treated as having been paid for at least 3 years
- you worked in the UK immediately before leaving
- you’re currently working abroad (or you worked while you were abroad)