ROFLMAOI asked screwfix about the high price and according to screwfix, the BG and appleby ones,
"The two items have different specifications and suitabilities. Therefore, this is reflected in the price: "
But not an unexpected response, when contacting a large company your chances of getting someone who really knows what is going on and is authorised to talk about it is essentially zero.
I'm still going with the explanation that this is a botched implementation of "dropshipping", where they didn't have any easy way to handle shipping/handling charges for third party warehouses, so they just slapped a steep shipping charge on every product.

