When I queried this, I had the following reply from the Puzzles Editor & I apologise for the mindslip that meant I neglected to post it here -
"As I understand it the puzzle is currently between sponsors. I am sorry that this wasn't explained on the pages.
I have forwarded your comments to The Mail On Sunday. They do monitor things like this quite closely. I hope somebody will be back in touch with you with a fuller explanation than I have been able to provide."
I have not received anything further from the MOS.
HTH :-)