The only "proper" way to do this is to persuade them to grant you exclusive selling rights in the UK. This would ensure that you would get a "cut" of all items sold here, and they would be in breach of contract to deal direct...however you have to ask yourself why would they do this? Can you offer them something that no-one else can? If they already sell the product here, then it is unlikely. If they do not, then it could be argued that you are offering them the opportunity to sell into a new market, and you can offer the expertise to do this, on the basis of exclusive rights! I guess one means of persuasion may be to buy loads of stock from them, and guarantee a sales level. Without meaning to be judgemental, the tone of your question suggests that if this is worth pursuing, then you need some expert advice. Good luck!