The Location, Location, Location presenters’ friendship has been a constant subject of speculation.
Married Spencer said that they ended up in the hotel bedroom because Allsopp, who has two children with her partner Ben Andersen, had locked herself out of the room.
“I was downstairs in reception, and Kirstie rang,” he told Radio Times magazine.
“She said, ‘Darling, I’ve locked myself out of my room,’ so I go up with a new card, let her in and wait while she packs and brushes her teeth.
“Then we walk out, I’m wheeling her suitcase, people notice.”
The pair are presenting new Channel 4 show Love It Or List It, in which couples decide whether to move house or stay and make improvements on their home.
Allsopp admitted she would like to be housing minister but dismissed rumours which had linked her to the Kensington seat vacated by Conservative MP Malcolm Rifkind.