London's premier index pushed to a record high and the pound sunk after a shock poll showed the Conservatives' lead was slipping ahead of the General Election.
The FTSE 100 Index hit a mid-session record of 7,554.21, before rising 29.92 points to close at an all-time high of 7,547.63.
The pound dropped to a two-month low against the euro, slipping 0.9% to 1.143, after Theresa May's advantage over Labour narrowed to just five points in the first opinion poll since Monday night's suicide bomb attack in Manchester.
A YouGov survey put the Conservatives down a point on the previous week on 43% and Labour up three on 38%, with the Liberal Democrats up one on 10% and Ukip up one on 4%.
Sterling was also tracking a one-month low versus the US dollar, down 1.2% to 1.278, with the greenback compounding the pound's woes by rising on better-than-expected economic data from America.
Blue-chip companies, which report in US dollars or euros, get a lift on the FTSE 100 Index when the pound suffers because their earnings benefit from a more favourable currency translation.
Michael Hewson, chief market analyst at CMC Markets UK, said: "With the pound already under pressure due to weaker than expected economic data, this surprise poll has acted as an additional catalyst in pushing the pound to a two month low against the euro and its lowest level this month against the US dollar.
"Having started the campaign on a 'strong and stable' footing, recent policy missteps by Mrs May have seen the election campaign take on the look of an 'ugly contest' of mediocre candidates, and that appears to be being reflected in the recent performance of the pound."
Away from the top-tier, the FTSE 250 Index, seen as a better barometer of the health of UK business, also reached an all-time closing high, rising 57.34 to 20,024.92.
Across Europe, Germany's Dax was down 0.2% and the Cac 40 in France was 0.1% lower.
The price of oil was up 0.4% to 51.65 US dollars a barrel during a tumultuous day's trading in the wake of Thursday's Opec meeting.
The cartel extended an existing deal to curb production to help tackle the global glut of Brent crude, but batted away calls to make deeper cuts.
In UK stocks, database and exhibitions firm Informa was in the ascendency thanks to a positive trading update.
Shares rose close to 6%, or 38p to 688.5p, after the firm said it was on track to record its fourth year of growth on the bounce.
Group chief executive Stephen Carter said: "We continue to make good progress in 2017, benefiting from our strengthened operating capabilities, increased scale and international breadth.
"We remain on track for a fourth consecutive year of growth in revenue, earnings and cashflow."
Drugs giant GlaxoSmithKline was also enjoying an uplift following a broker upgrade, rising 25.5p to 1,643.5p.
In contrast, Royal Bank of Scotland dropped 4.4p to 261.6p, as investors continued to digest Thursday's announcement that a multimillion-pound High Court action brought by thousands of shareholders against the bank would be adjourned until June 7.
The civil case was due to begin on Monday and last for 14 weeks, but the judge overseeing the action has granted a series of adjournments to allow settlement discussions to continue between investors and the bank.
On the FTSE 250, the Restaurant Group raced ahead after it said full-year pre-tax profits would be in line with expectations.
Shares were up 33.2p to 350.6p despite the struggling owner of Frankie & Benny's enduring another period of tough trading , with like-for-like sales dropping 1.8% in the 20 weeks to May 21.
The biggest risers on the FTSE 100 Index were Informa up 38p to 688.5p, Johnson Matthey up 80p to 3,175p, Rolls-Royce Holdings up 21.5p to 873p, British American Tobacco up 96p to 5,591p.
The biggest fallers on the FTSE 100 Index were Lloyds Banking Group down 1.4p to 71.74p, Shire down 86.5p to 4,651.5p, United Utilities Group down 19p to 1,035p, Royal Bank of Scotland down 4.4p to 261.6p.