RSUs and redundancy - base cost of shares for cgt?

My Client was given some RSUs as part of his redundancy package.  Employer took legal advice and is so convinced that these can form part of the redundancy settlement that no paye or ni was deducted on the first £30k when the shares were sold as part of the deal. 

I am aware that this may not be correct, but if we can just assume for now that it is correct, what is client's base cost for these shares in the cgt comps?  £30k or £0??