Flies in the house

[Chattyrats]

Came back from holiday to discover loads of flies in main bedroom. Absolutely gross. Had everything out and eventually found the cat had kindly gifted us a dead mouse which he'd hidden under the bed. Obviously removed it and cleaned EVERYTHING. But still found 2 more disgusting flies today. When will they be gone? Do I need to clean everything again? Yuck yuck yuck yuck.

They are just flies, and it's summer - I get a few flies (and butterflies/moths/bees/etc) in my house throughout the day because the windows are open.

It's normal for there to be flies at this time of year.