help with contract clause advice/suggestion needed Urgently.

Hi
I contract through my limited company and this question is related to the contract agreement for my next contract role.

Here is the query.
Last year in Oct 2012 I finished contracting for client through an agency X.
Now I have another contract offer for the same client but through a different agency Y.

I have not yet signed the contract with Y . But while going through my last contract agreement with agency X (the previous agency), I found that there is this clause.

"The Service Provider and its Directors undertake that they shall not and that they shall procure that the Consultant(s) shall not enter into
any agreement, whether directly or indirectly, to supply services of a similar nature to the Client or a subsidiary or associated company of
the Client or to the Client’s clients, other than through the Company for a period of 12 months following the termination of the Agreement."

So I am in a bit of pickle now. If I go ahead with the contract through the new agency Y I will be breaching the clause above and in this case what are the legal implications and risks.

Thanks for any help.