Thanks for the replies guys. I will go and find it tomorrow as the job is a long way from where I live.
Don't worry I will do as you say and not clean it.
I take it there is the possibility that it is not just any average halfpenny as long as it is what I remember it as when I told dad.
My dad spoke to me later and said " you must be mistaken son, it must have been king George".
I'm assuming king George half pennies are a lot more common.
Very interesting by the way about the putting of coins under thresholds. I am a carpenter, maybe I should start doing the same. Instead of a comedic remarks written on the reverse side of things for future chippies to find.
Regardless of the value of the coins put under thresholds and such like, I wonder what the trades person who put the coin there would be thinking if they could see you find the coin.
I would like to think that the remarks I put would raise a smile on what may be a horrible day up to that point.