1970 the property.
How accurate do you perceieve this date to be. Unearthed lighting circuits were permitted (as long as no class 1 accessories) upto 1966, now it would seem that this property was built after that going on that date, however if thats just a building surveyours best guess, then could they be 5 or more years out?
Can we have a picture of the schedule of circuit details (may as well have schedule as tests as well)
What is the age of the installation stated on the EICR (its possible to be pretty close with the date of an installation if you know what belonged to what era)