"The extraordinary moment Labour MP Lloyd Russell-Moyle picks up the mace and walks it over the line during proceedings in the House of Commons"

"The parliamentary mace symbolises royal authority; without it the House cannot meet or pass laws"

Daily Mail:

A Labour MP was suspended from the Commons after he picked up the ceremonial mace in protest at the Brexit vote being deferred.

...

In 2009, Labour's John McDonnell - now the Shadow Chancellor was suspended from the Commons for five days after he picked up the mace during heated exchanges on the Government's decision to go ahead with a third runway at Heathrow.

Something very Brexity about this. Grabbed at a symbol of power because he wanted to show off an angry pose, then realised he had no idea what he should do with it once he had it. https://t.co/fVxK8RA5sF

— Stephen Tall (@stephentall) December 10, 2018