Engineers Certificate of Compliance

We're currently in the process of selling our home. Our solicitor has asked for an engineers certificate of compliance with planning permission and building regulations for the construction of the house.

We have the original planning approval document to hand from the local council. Am I right in interpreting this is all what is needed, or do they also require us to engage an engineer and pay for an up to date engineers report? I understand the buyer would want to do this but surely the seller need not? For reference, the house is 40+ years old.

2 certs being asked for here.
B regs only came into existence circa '92 so compliance to same would be moot if house constructed prior to this.
Yes, you would need to engage a professional for the compliance to PP cert.

It is the vendor's responsibility to prove that the property is in compliance with planning and the building regulations that were in force at the time of original construction, or any subsequent development. You will need to engage and pay for an engineer to produce the required certs.

Without these, you may be able to sell to a cash buyer who knows their stuff and has satisfied themselves as to the situation or is willing to take a chance, but mortgage providers are getting a lot more particular about ensuring compliance is in order to protect their own interests.