For an hour or so on Monday afternoon the City's famous index of shares in leading British listed companies, the FTSE 100, popped its head, for the first time in its history, into the nose bleed territory above the 8,900 mark.

It was yet another all-time high achieved in a remarkable rally since the start of the year that has driven the index up around 500 points, or six per cent, already in 2025. That's helped lift the gloom that has enveloped the Square Mile.

Inevitably the Footsie, as it is affectionately known, has fallen back a bit since then amid the geo-political car crash that is the looming global trade war. But not by much, and crucially, not nearly as far as the ailing stock markets of the USA.

Make no mistake, shares in British companies, for so long the "nobby no-mates" asset class, are suddenly back in fashion. Now every investor in town wants to play footsie with the Footsie. The pound has also had a good week, rising to $1.28 against the dollar, the highest since November.

So what has driven this sudden, and welcome, reappraisal of the UK and the London stock market? Analysts say there are many factors, some a "Trump dividend" connected with the arrival of the new president into The White House in January, and others entirely of Britain's own making.

First we need to talk about tariffs. This week the Oval Office confirmed import levies of 25 per cent on Canada and Mexico and doubled those on Chinese imports to 20 per cent.

This high stakes move and the tit for tat retaliation that has inevitably followed has spooked markets around the world, although there are some suggestions the Trump administration may rein them back.