The beloved feline has been poorly for some time according to the Sun on Sunday – with officials being said to be preparing a comms strategy in the case of his death.
It is thought that an official social media post from the Government will announce the sad news.
A Westminster source said: “Larry is much loved not only in Downing Street but across the country.
“No one wants to think the worst, but unfortunately we must prepare for it.”
Tabby stray Larry is 16 years-old and has been in Downing Street since 2011 – when he was adopted by former Prime Minister David Cameron.
Though intended to be a family pet, he remained after the Camerons left in 2016 and was charged with demousing the Prime Minister’s official residence.
Stray tabby cat Larry is 16 years-old – which is around 84 in cat years.
Downing Street’s website states: “Larry spends his days greeting guests to the house, inspecting security defences and testing antique furniture for napping quality.
“His day-to-day responsibilities also include contemplating a solution to the mouse occupancy of the house.”