Green’s Dictionary of Slang

(UK society) sexual intercourse during the day.

1982		Barr & York Sloane Ranger Hbk 158: Interior decorating n. Sex in the daytime.
1999		D. Lypchuk ‘A dirty little story’ in eye mag. 8 July 🌐 ‘Sure,’ she said. ‘I wouldn’t mind doing some interior decorating.’.