Electric blanket on origins pocket sprung 1500

I previously asked whether it is ok to use an electric blanket on an origins 1500 pocket sprung mattress.
You replied; "Hi Angela,
You can use an electric blanket on this mattress, however, what I would suggest is that you place a protector on the mattress and then the electric blanket.
Kind regards "
Is it advised to do it that way to protect the mattress from direct contact with heat or is it advised to put the protector, then the electric blanket for better heat distribution?
We've now had the bed nearly a week and we love it! It makes getting up in the mornings so much harder as it's so comfortable!
Thanks again.