Though the UK and the EU have agreed a Trade and Co-operation Agreement, massive uncertainties still swirl around the future of their relationship. Here are 5, in a short thread. @CER_London 1/6

The TCA says virtually nothing about future co-operation on foreign policy and defence; the UK wanted no institutional links. But will a future UK govt see the case for ties that would enable it to learn what the EU governments are thinking, and influence them? 2/6

Will the new quasi-border in the Irish Sea prove politically sustainable? Unionists (and some Tories) will hate the checks on goods going from GB to NI, and the fact that NI stays partly in EU single market & customs union. Some may be tempted to tear up the NI Protocol. 3/6

The UK has won the right to abandon EU standards on social, environment, state aid - at great cost in reduced mkt access. But will UK choose to exercise that right, to achieve 'Singapore-on-Thames', or will it in practice stay closely aligned, as many businesses would prefer? 4/6

Will the new dispute settlement mechanism be working overtime, for years ahead, with both sides taking an antagonistic and legalistic approach? Or will high-level summits and chats rebuild trust and foster a co-operative relationship? 5/6

The answer to these questions depends on the future of the Tory party. Will the nationalist-nativist tendency stay in charge, seeking to win votes and good headlines through bashing Brussels? Or will the moderates recover their strength and pursue pro-business policies? END