Visit to a consultant (in his "rooms" ) Cash only No cheques,no laser cards,no visa ?

They can claim all they want. But, if they conspire with the vendor to evade VAT, then of course they are legally responsible for the consequences.

Is that actually the case? How could the purchaser be prosecuted...surely they cannot be liable for the vendor's tax returns?
 

OK. I give up. You win.
 
Thanks for that....wasn't aware of that at all. A few prosecutions in this area would go a long way to stamping out the black economy.
the black economy will never be stamped out, it has always been around and always florishes in times of recssion, its just human nature at work.