All but one sector was in the black in early deals on Britain's main stock index, which rose 0.6%. The domestically-focussed FTSE 250 added 0.4% by 0708 GMT.

Firms that book a major chunk of revenue in U.S. dollars also boosted the FTSE 100 as the pound fell on lingering worries of a no-deal Brexit, with eurosceptic Boris Johnson widely tipped to win the Conservative Party leadership and become the next Prime Minister.

Tesco, Saisnbury's and Morrisons were down between 1.1% and 2.3% after data from market researcher Kantar showed sales at all of Britain's big four supermarket groups slowed over the latest 12 week period.