Perhaps they saved up enough money to go to the grand final but had to go to the ashes instead for some September action with no money left over for cricket attire? But I think the more likely reason is they have spent a few weeks drinking copious amounts of English ale and never got around to doing their washing so they had to dig deep and pull out the only thing they had left to wear that was clean (not that the poms would notice anyway given showering is optional).
Reminds me of a trip to Geelong in 2013 when I had to borrow a mates guernsey because I forgot mine and I’m sure it hadn’t been washed since 1998. Tomato sauce stains and a horrific stench but I still wore it with pride.