The benchmark FTSE 100 index ended the day up 29.92 points or 0.4% at 7,547.63, while the FTSE 250 closed up 57.34 points or 0.29% at 20,024.92.
The 250-share index was helped by a 10.5% rise in the shares of Restaurant Group.
The company - which owns chains such as Frankie & Benny's and Garfunkel's - said like-for-like sales fell 1.8% in the 20 weeks to 21 May.
However, this was an improvement on the 5.9% drop seen in the previous quarter.
In the FTSE 100, business media group Informa was the best performer, up 5.8%.
In a trading update, the company said it had seen "continued improvement" in the first four months of the year, adding it was on track to hit full-year expectations.
Banking stocks were out of favour, however, and saw some of the biggest falls in the FTSE 100. RBS shares dropped 1.65% while Barclays was down 1.1%.
The pound lost ground on the currency markets, which analysts put down to political uncertainty. Sterling fell 1.2% against the dollar to $1.2784 and was also 0.9% lower against the euro at 1.1442 euros.
UK share indexes have closed at record highs as the value of sterling slipped.