My right hon. Friend wrote a very wise paper, which I referred to in a previous exchange here. He will recognise that the negotiating balance changes at the end of the two-year period, so it is very important that we conclude the deal by then. The implementation is a different matter; it may take time, and it does take time, but we cannot control that, whether we are putting in place a new customs arrangement or whatever it might be. So there are practicalities there, and it is the practicalities that will drive this.