Answer to a letter asking the same in Soldier Magazine....
"There have been similar observations regarding the appearance and use of normal boot polish on the new sets of brown boots and, unfortunately, there appears to be no immediate solution to hand.
The range of new footwear which are all commercial off the shelf items, are made from a mix of natural and synthetic materials.
The manufacturer produces an own-brand range of polishes (go to
www.haix-bootstore.com for details) but you should be able to use standard cleaning products too.
You might have to indulge in some trial and error regarding the choice of colour though.
The Defence Clothing Team is aware of the user feedback and this will, no doubt, influence the specification of the next generation of issued boots."