A building can have more than one meaningful date: original construction, later extensions and conversion into flats. Decide which question you are trying to answer before treating any recorded date as the age of the whole property.
What to check.
Start with the available records
Look for an EPC construction age band, planning references and documents from the seller. Keep an age range as a range rather than converting it into a precise year.
Build a timeline of changes
Separate the original building from extensions and conversions. Compare source dates and note where an address or property layout changed.
Find corroborating evidence
Ask the relevant council or archive about historical records, and discuss construction clues with a surveyor. A useful conclusion may be a supported range rather than an exact year.
What the evidence cannot tell you.
An EPC age band is not a verified construction date. A registration date, first recorded sale or recent certificate date should not be assumed to mark when the house was built.