Alternatively found one at Asda (have never seen it before myself though) for £16 with £3 delivery. 84x54x44cm external dimensions. Someone’s posted cage setup on the 2 pack version (£25!) for size reference.
https://direct.asda.com/george/georg...efault,pd.html
And one on amazon for £30 that I can’t link because I’m on the app, called Crystal 133L box. Someone’s used it as a mouse cage and posted a photo too. It is narrow as dimensions are 99x39.5x42cm so internally would be narrower. Best for a dwarf really and more expensive.