Rabbit safe shampoo (UK)

I know rabbits should never be washed, but both my buns are now in a bit of a pickle and need to be cleaned properly.

Both are elder buns, arthritic, but have both just gone into stasis together.

Between the stress of everything and liquid feeds, they have a lot of bits of liquid feeds stuck to them (working out when dry) and have wee'd om each other. With the warm temp and risk of flystike, I'm looking to give them spot baths on the affected areas but can anyone recommend a rabbit safe shampoo? TIA