Gonzo,
From what I can remember Heathrow assessments came in about 93-94.The reason I recall is that I had the same gun as Data Dad had,pointed at my head by Nats in 92.Your going to LL,no choice etc.By 94 you had to be assessed.
Maybe that's for Atco 3,and the ones you are taking about are Atco 2. Perhaps we should introduce an assessment as well for incomers at our little station.Takes as long to validate,double the runways,4 terminals as well and we have to do radar.After all the reason for the procedure is sound,and you would expect that moving to another unit.