That would be a serious blow to the UK and its Nato allies. After an initial period of relief, the result would surely be more pressure for increased defence spending across Europe and increased anxiety about what President Putin would do next, causing a fall in the confidence of consumers, businesses and financial markets.
But it is by no means certain that President Trump would put such pressure on Ukraine.
Meanwhile, President Putin has surely been holding out in the hope of a Trump victory forcing Ukraine to the negotiating table. If Trump wins but intense pressure on Ukraine fails to materialise, then Putin might well feel he has to negotiate and the outcome might not be so unfavourable to Ukraine, and hence to the UK and the West in general.
Donald Trump has made it clear he intends to use energy prices as a foreign policy weapon. He wants to do whatever he can to boost oil, coal and gas production, leading to lower energy prices, which would put pressure on the financial position of both Iran and Russia.
The hope would be that we would end up with (at least temporarily) lower global inflation and a long-term solution to the Russia/Ukraine conflict. But it remains to be seen what Trump could achieve.
The policy measure that threatens to have the largest direct impact on the UK is Trump’s proposal to introduce a 60pc tariff on imports from China and a 10pc tariff on imports from everywhere else. This is especially important to us because UK goods exports to the United States amount to about 7pc of all our exports, while our services exports to the US amount to about 15pc of total UK exports.
Accordingly, you might think that if the UK were to face a 10pc tariff on exports to the US then the economic impact here could be pretty serious.
In practice, however, I doubt that it would be. The evidence is that as the imposition of a tariff put up the US price of British exports, the responsiveness of US purchasers would not be great. Moreover, tariffs are not normally imposed on services, which make up the bulk of our exports to America.