The index hit all-time record highs of 7,554.21 points in afternoon trading, with the FTSE 100 closing at its highest ever, 7,547.63 points.
Informa led the index with a 5.84 per cent gain, putting it on track for its highest close since the middle of January after a weak performance year-to-date.
The publisher and events company said it had met full-year expectations and was enjoying “strengthened operating capabilities, increased scale and international breadth”.
Strengthening gold prices also boosted the yellow metal specialists among the mining cohort. Gold futures gained around 0.8 per cent during the trading day to break above $1,270 per troy ounce.
Randgold Resources gained 1.48 per cent, while Fresnillo shares added 0.32 per cent at the time of writing.
However, the main driver for broad-based gains was the weakness of the British pound against the US dollar. A strong dollar benefits FTSE-listed multinationals who earn in dollars but report profits in sterling.
The pound’s fall by more than one per cent to below $1.28 by the end of stock trading was driven by a poll overnight which showed Prime Minister Theresa May’s lead over Jeremy Corbyn’s Labour shrinking to only five points, the narrowest since the start of the election campaign.
Currency traders have previously bet on an increased majority for May’s Conservatives to strengthen her hand in pursuing a pragmatic Brexit deal with the EU, but a diminished majority would increase the prospects of a hung Parliament.
Chris Saint, an analyst at Hargreaves Lansdown, said: “This adds an extra strand to political risks currently weighing on the pound, with markets previously taking it almost for granted that a larger parliamentary majority would hand Mrs May a stronger negotiating position in upcoming Brexit talks.”