The blue-chip FTSE 100 index was up 0.3%, while the domestically focused mid-cap FTSE 250 index dipped 0.1%, dragged by weakness in technology and industrial stocks.
Travel-related stocks climbed 2%, with Flutter Entertainment, Compass Group, Just Eat Takeaway.com and InterContinental Hotels Group among the top gainers.
However, a report said Britain's proposed June 21 lifting of lockdowns could be delayed by a fortnight as COVID-19 cases continue to mount.
"In news there's nothing really to warrant this optimism for the travel sector but maybe people are looking through these events as short-term developments that eventually will sort themselves out and people will be able to travel again," said Andrea Cicione, head of strategy at TS Lombard.
"I think it's a bit of a bet, but probably is the right one."
After breaching the 7,000 mark in mid-April, the export-heavy FTSE 100 was on course to post a fifth month of gains as a gradual reopening from COVID-19 lockdowns sparks optimism around a faster economic recovery.
Miners including Rio Tinto, Anglo American, Glencore and BHP rose between 0.1% and 1%.
Adding to the upbeat mood, Intermediate Capital Group climbed 5.9% to a record high, after the alternative asset manager posted a 19% jump in its annual third-party assets under management.
British American Tobacco added 0.4% after it raised its annual revenue growth forecast to more than 5% at constant currency.
Aviva gained 2.7% after activist investor Cevian Capital took a 4.95% stake in the British insurer.
(Reporting by Devik Jain and Amal S in Bengaluru; Editing by Subhranshu Sahu and Bernadette Baum)
By Amal S