After a flat start the FTSE 100 mounted an afternoon rally as the pound dipped ahead of tomorrow's triggering of Article 50 by the prime minister, heralding the start of the UK's two-year withdrawal from the European Union.
Approaching close the blue-chip index had gained 48 points, or 0.7%, to 7,342 with the pound 0.35% weaker at $1.2509 against the dollar.
Wolseley (WOS) was the biggest riser on the index, up 5%, or £2.47, at £51.32 as the heating and plumbing products supplier reported a 25% jump in first-half profit.
Among 'mid cap' stocks AA (AAAA) jumped to the op of the FTSE 250, 5.7% higher at 270.5p after the motoring group posted inline full-year profits of £403 million and said it had seen a positive start to the new financial year.
OneSavings Bank (OSBO) was the biggest faller, down 6% at 395.7p as investment group JC Flowers sold a 10% stake in the challenger bank.
The UK advanced following a more positive close on Wall Street overnight after yesterday's 'Trump tantrum', buoyed by a late recovery in US stock markets from the lows hit following US president Donald Trump's defeat over healthcare reforms.
'Despite closing in the red for an eighth consecutive session, its worst losing streak since 2011, the Dow Jones managed to pull itself back from the brink last night, leading to a far cheerier open from Europe,' said Connor Campbell, financial analyst at Spreadex.
'With yesterday's market tantrum seemingly out of their system, investors appear to be willing to give Trump the benefit of the doubt, once again eyeing his tax reform promises as justification for the current levels.'
This afternoon the S&P 5oo index gained nine points or 0.4% to 2,351, helped by strong consumer data which offset further falls in healthcare stocks.