The mystery of the missing background

I didn't realise that I'd forgotten about the background in the last two panels until I started on the colouring.

The sound effect 'Gronff' is one I've borrowed from The Perishers, (see previous entries). Of course nowadays the accepted sound effect for cats eating is 'Nom nom nom' but that seems far too polite to me.

The Perishers, written by Maurice Dodd, Drawn by Dennis Collins. 1968.