Bill Gates made a sly dig at Brexit while on stage in London

It sounds like Bill Gates doesn't think Brexit is a particularly smart idea.

On Thursday, the Microsoft cofounder-turned-billionaire philanthropist gave a speech at the annual meeting in London of his Grand Challenges charity initiative - and found the time to slip in a couple of sly political digs.

Early in his speech, Gates discussed a vote by the British public to award funding to research into antibiotic resistance in 2014.

"The British public voted, in this case I think wisely," the American former executive joked - in what appears to be a dig at the wisdom of Britain's recent vote to leave the European Union.

The aside prompted laughter from the audience, and was made while Priti Patel, the UK government minister in charge of international development was on stage. Patel was a leading campaigner for Brexit in the run-up to the vote, and it's not clear from footage of the event whether she laughed.

Gates didn't explicitly reference Brexit when making the joke, but it seems fairly clear that he was referring to the referendum, and has been interpreted as such from numerous members of the audience posting on Twitter.

Later in the event, discussing efforts to create a vaccine for malaria, he joked that it's lucky people can't vote to "un-invent" one once it is created - something people are also interpreting as a jibe at the wisdom of voting to leave the EU.

Gates didn't confine his subtle political jabs to Brexit. Later in his speech he said "you can't build a wall" to keep out deadly diseases - echoing caustic Republican US presidential nominee Donald Trump's promises to build a wall between the US and Mexico to keep out illegal immigrants.

Here's a video of Bill Gates' speech. He makes the first remark about "wisely" voting around the 1m30 mark.