Will a brief lack of lead substitute damage the engine of my Series III Land Rover?

I normally add some lead substitute to the tank of our 1980's Series III Land Rover. The other day I didn't (because the garage didn't have any on its shelves and I then forgot about it). So with a full tank of unleaded I went for a 60 mile drive up and down the hills of Exmoor. Do you think the absence of a substitute would have led to damage to the engine? The only real difference since the drive is that the car is tending to stall on tickover unless a bit of choke is used - though there may be a coincidental issue with the engine apparently not warming up properly. As ever I'd be very grateful for your advice.

Asked on 6 February 2012 by PK, Wimbledon

Answered by Honest John
No. The stuff coats the valves and valve seats and stays there for some time. But obviously it will eventually start to disappear.
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