ROOM FOR COMPROMISE?

For its part, the EU is sticking to its CETA or EEA offer, without plus or minus. Whether there is room for a compromise between the two positions and at what price, in terms of British contributions to the EU budget and with respect of ECJ decisions, is what the negotiations of phase two will really be about, said Maria Demertzis, deputy director of the Bruegel think tank based in Brussels.

"Given the tight schedule of phase two, which requires a deal to be reached by October, November 2018, CETA-plus looks much more feasible than EEA-minus," she said in an analysis co-authored with Bruegel's senior research fellow Andre Sapir.

"For the EU, CETA plus would avoid getting into the discussion on the indivisibility of the single market's four freedoms, which it considers sacrosanct at this stage and which EEA-minus would imply," Demertzis said.

For Britain, CETA-plus would probably require less contribution to the EU budget and less respect of ECJ decisions than EEA-minus, and therefore be easier to accept politically," she added.