A very big thanks to you all.
My vet has come up trumps. A 5 litre container of unfragranced for £24.50 plus VAT. A blinding result
Lynn's thought is a good one. Most, if not all vets, use Trigene along with a majority of boarding catteries and a lot of rescues. If you are good terms with your vet and a good customer, tap into his purchasing power.
Now where are those trays??