London's main index, the FTSE 100, has surged to a fresh record high for the second time in less than a week.
The FTSE 100 index closed over 1% higher at 7,859.17, comfortably above its previous high of 7,787 on 17 May.
An easing of trade tensions between the US and China cheered investors, analysts said.
The dollar rose after the deal, boosting UK-listed miners, oil firms and banks which earn much of their money in dollars.
The pound was down 0.3% against both the dollar and the euro, trading at $1.3431 and €1.1406 respectively.
Neil Wilson, chief market analyst at markets.com, credited the stronger dollar with driving most of the FTSE 100's gains.
He warned that the upbeat mood among investors may not last, given that the agreement between China and the US - which avoids a punishing trade war for now - lacked concrete details.
"The sides could return to blows quickly - there may not be much weight behind the move and the positivity could float off into the atmosphere on the emergence of any downbeat news," he said.
Mr Wilson said whether the FTSE continued to gain ground would depend largely on what happened to the pound, which was likely to be volatile with the start of a fresh round of Brexit talks on Tuesday.
Retail firms were some of the biggest risers in the FTSE 100 on Monday.
Marks and Spencer, Sainsbury and Next rose between 2 and 4%, putting them among the top ten biggest risers.
There were just eight firms on the FTSE 100 which ended the day lower.
BT, drugs firm Shire and consumer goods firm Reckitt Benckiser were among the few shares to lose ground.