The summer drinks brand, which is famous for the ‘It’s Pimm’s o’clock’ slogan, has made a "generous offer" to sponsor the dial of Elizabeth Tower, which is commonly known as Big Ben.
Marketers at Pimm’s have persuaded officials at the Houses of Parliament to allow them to install a 23-ft transparent vinyl overlay on the clock face, but behind its hands.
The overlay displays the Pimm’s logo while protecting the clock face and was installed in the early hours of this morning by a team of abseiling workers.
Pimm’s senior brand manager, Jo Segesser, said: "Pimm’s O’Clock is a national catchphrase and so the opportunity for us to sponsor Britain’s most famous clock was too good to pass up."
TV broadcaster Peter Sissons was on site this morning to report on the landmark event.
Update: In case you did not clock it, this was an April Fools' story. For a round-up of this year's best April Fools' stories click here.