Ms Pelosi had asked the president to postpone his State of the Union address, as the partial federal government shutdown over the Mexican wall debacle moves into its second month, so he asks her to postpone her trip or organise and pay for her own flights.

But this time, unlike other occasions on which Mr Trump offends liberal sensitivities, there is a but: Mr Trump makes a fair point when he doubts that the cost of her journey could be justified while 800,000 federal government workers are either working without pay or simply not working.

Was Ms Pelosi’s journey really necessary? Her plan to meet and thank US troops in Afghanistan was unlikely to have aroused much excitement in the ranks, where the preference might have been for Lady Gaga, and as for her business with Nato people in Brussels, hasn’t she heard of Skype?

The president’s isolationist instincts also played a part in his decision to pull his cabinet’s delegation out of next week’s World Economic Forum in Davos, the annual assembly of the great, good and not-so-good — a four-day beano for the global elite. Yet there is a question to be asked, too, about the value or otherwise of this jamboree, other than to Swiss hotels.

Among the participants will be Zimbabwe’s president Emmerson Mnangagwa (taking time off from suppressing protests), Germany’s Angela Merkel (her swansong appearance) and Leo Varadkar.

Along with Mr Trump, Ms May and Mr Macron are otherwise engaged. The theme of this year’s WEF is ‘Globalisation 4.0: Shaping a Global Architecture in the Age of the Fourth Industrial Revolution’, in contrast to last year’s ‘Creating a Shared Future in a Fractured World’. Perhaps the Taoiseach will tell us all about it on his return?