The top-flight index of Britain’s biggest listed companies rose 37.91 points to 7106.08 on its first day of trading since Christmas amid the traditionally strong ‘Santa rally’ between now and the New Year.
The market broke above its previous closing high of 7103.98 set on April 27 last year.
The Daily Express, which publicly backed leaving the EU ahead of June’s referendum, described the news as a “Brexit bonanza”.
“The FTSE 100 has hit an all-time high as the UK economy continues to go from strength to strength after the country decided to leave the European Union,” the paper wrote.
However one market analyst told the Press Association that long-toothed traders have noticed a traditional period of growth between Christmas and New Year before, pre-Brexit vote.
David Cheetham, market analyst at online trading group XTB, said: “Observers of the markets have for many years noticed a strong propensity for stocks to rise in the period between Christmas and the New Year and this phenomenon appears to be playing out once more.”
But Britain’s decision to leave the EU did help boost the FTSE in one way - as global traders took advantage of the wallowing value of Sterling.
Cheetham added that post-Brexit currency fluctuations, namely the plummeting value of the pound against the US dollar and a raft of currencies, was also helping the FTSE gain ground.
Stocks in mining firms and commodities performed particularly well.
It comes a day after a pro-Brexit think tank argued Britain would benefit from an additional £24bn a year by leaving the EU.