I know it would only be a short stop gap solution to many ... given some boats fuel consumption ... but to many sail it could be a longer term answer.
I don't live in UK much - so I don't follow the rules and regs too closely unless they are of particular interest on a subject I'm involved in etc. - but :
While Red is still a viable legal fuel for boating ... what stops an enterprising person buying up repeated lots ... stocking up so to speak ... a small addition of biocide maybe to help storage ... a significant stock could be built up surely ...
Later when red is not available - cut into the stock say mixing with white ? As long as you have the sales receipts and especially with a sail boat that often fuel is long term in tank ... ??
Daft idea I know ... but ??