T4 Autosleeper Clubman GL Unwanted Visitors

...needs to be dealt with asap. Mice are very bad news in any vehicle, especially underbonnet areas where chewed wiring can cause serious and expensive problems.
My advice is to try a modern mousetrap, I can particularly recommend "the big cheese", a bright red and yellow pack of two. no flimsy wires to set, it just pulls back on a ratchet. Self baited, just remove a cap, so nothing messy to deal with. The modern design means there is only one way the mouse can get in, so it's an instant neck target, no lingering wounding.
I have used these at home with a lot of success, we used to have a couple of mice mopping up at the bottom of our garden bird feeder....then there was another one...and then appeared a baby...so enough was enough - for the tree the feeder was on is right next to our campervan ! - a "big cheese" was put down, and, instant result, at the end of the first week there were 17 mice who would never get into our 'van.