Members of the Cabinet appear to be following Environment Secretary Michael Gove's lead in making the switch to reusable coffee cups.
Ministers were seen leaving a Cabinet meeting clutching reusable cups - although some were still in their boxes.
It comes after the Environment Secretary was spotted strolling into Downing Street last week with one of the "keep cups", having previously been photographed holding a disposable coffee cup.
There is growing pressure to tackle the 2.5 billion disposable coffee cups the UK gets through every year, with almost all of them incinerated, exported or sent to landfill because their plastic lining makes them costly to recycle.
MPs on the Environmental Audit Committee have called for a 25p "latte levy" on the disposable cups, on top of the price of a hot drink, with the revenue used to pay for improved recycling facilities.
Having made the switch, ministers will be able to benefit from voluntary efforts by some coffee shop chains to give customers money off for using reusable cups, with Pret A Manger recently doubling its discount to 50p.
It is in keeping with the Government's drive to reduce plastic, with Prime Minister Theresa May pledging to eliminate all avoidable plastic waste within 25 years as she unveils the Government's long-term plan for the environment.
But a recent freedom of information request revealed the Environment Department (Defra) and the House of Commons had each got through millions of disposable cups in the past few years.
It now seems a decision has been made to lead by example from the top.