UK shares joined in a European rally in equities following the first round of France's presidential vote that also sparked a jump in the euro.
The FTSE 100 index clawed back some of the losses triggered by last week's announcement of a general election, closing up 2% at 7,264.68.
France's Cac 40 index soared 4% to 5,268.85 and Germany's Dax climbed 3.4% to 12,454.98.
Bank shares across European markets were among the best performers.
The FTSE 250 Index, seen as a better barometer of the health of UK business than the more international FTSE 100, rose 1.3% to reach an all-time closing high of 19,602.83.
The rise in shares follows news that centrist Emmanuel Macron topped the voting in France on Sunday, going through to the final round with far-right candidate Marine Le Pen.
Markets now expect Mr Macron to beat Ms Le Pen in the second round of the vote, installing a French president seen by investors as pro-Europe and pro-business.
Barclays finished 5.4% up, Standard Chartered advanced 4.75%, and Royal Bank of Scotland rose 3.96%.
Energy stocks were among a small number of fallers, with investors reacting to news that the Tory manifesto may include a policy to cap energy bills.
Centrica and SSE were among only three FTSE 100 stocks to fall, ending down 3.5% and 1.9% respectively.
The other faller was Randgold Resources, 1.4% off as the price of gold, seen as a safe-haven asset, fell more than 1%.
On the currency markets, the euro charged ahead.
Sterling was down 1.3% against the euro at 1.17, while the pound dropped 0.2% versus the US dollar at 1.27.
On the oil markets, Brent crude fell 0.8% to $51.55 a barrel amid concerns over an increase in US drilling activity.