The pound has continued its descent amid growing fears the UK will leave the European Union without a deal, with chancellor Philip Hammond expected to argue a no-deal Brexit would be a betrayal of the referendum result.
Sterling fell below $1.27 for the first time since January, trading a third of a cent lower at $1.269 against the dollar. The pound has now fallen 3.7% since hitting $1.317 earlier this month, after talks between the Conservative party and Labour over a Brexit deal collapsed and Prime Minister Theresa May agreed to set a timetable for her departure.
As May prepares to bring her Brexit deal to parliament for a fourth time, Hammond is due to warn against a no-deal Brexit in a speech to business leaders and politicians.
'The 2016 Leave campaign was clear that we would leave with a deal,' he will say.
'So to advocate for a "no deal" is to hijack the result of the referendum, and in doing so, knowingly to inflict damage on our economy and our living standards. Because all the preparation in the world will not avoid the consequences of no deal.'
The pound's fall boosted the FTSE 100's international earners, helping the index add 23 points, or 0.3%, to 7,334.
Banks were among the risers as investors were buoyed by the US easing restrictions on Chinese telecom giant Huawei.
On the FTSE 250, Galliford Try (GFRD) surged 11.6% to 598.5p after the house builder announced plans to cut 350 jobs.
UDG Healthcare (UDG) rose 6% to 694.5p after raising full-year earnings guidance.
Among small-cap stocks, Thomas Cook (TCG) recovered some ground after three days of heavy falls, rising 11.7% to 11.5p. But the shares remain 50% lower since Thursday's profit warning, which prompted analysts at Citigroup to rate the stock as worthless.