The FTSE 100 Index, Britain's benchmark stock market gauge, increased by 1.34 percent, or 87.61 points, to 6,608.59 points on Wednesday.
The London stock index bounced back strongly on Wednesday after a continuous slump over the previous two days. Investors continued to digest the latest news on Greece's precarious financial situation.
Greece became the first developed country in arrears to the International Monetary Fund (IMF), heading to an abrupt default and possible "Grexit" should last-minute efforts to reach a compromise debt deal on a third bailout program fail.
Markets did well on the speculation that Greece was reconsidering creditors' bailout proposals tabled last weekend, with only a handful of minor changes.
Royal Bank of Scotland Group's share price increased by 3.19 percent, topping the gainers of the blue chips. Merlin Entertainments, TUI AG, InterContinental Hotels Group and Barratt Developments increased by 3.16 percent, 3.01 percent, 2.92 percent and 2.85 percent respectively.
Randgold Resources Ltd. led the top losers of the blue chips with a share price drop of 1.63 percent, followed by Tesco (1.39 percent), Antofagasta (1.31 percent), Anglo American (0.91 percent) and Glencore (0.90 percent).