Investors overlooked concerns over Trump's steel tariff threats with gains spread across miners, utilities and banks helping the FTSE 100 rise 0.6% to 7,115 around midday.
Service sector growth picked up in February according to Markit's Purchasing Managers' Index. The index rose from 53 in January to 54.5 in February. A figure over 50 implies growth, while one under 50 suggests contraction.
Brent crude oil rallied 1.8% to $65.54 per barrel.