Pour out the beer from the can. Drink it! Pour in the wine and add the chopped garlic and thyme sprigs.
Get your chicken and give it a good rub with the butter - don't be shy, work your way into all the nooks and crannies. Season liberally with salt and pepper.
Gently ease the chicken onto the wine filled can. Use its little legs to help it stand upright. Nice!
Roast it for 1 hr plus, depending on the size of the chicken - test with a thermometer for doneness or use the skewer in the thigh method. Leave to rest. Keep the can and it's winey, thymey, garlicky goodness for the next step.
Meanwhile, mix the potatoes with the flour and parmesan. Splash a load of oil into a large roasting tin and heat it on the hob until it sizzles a piece of the potato. Gently pop the potatoes in and toss them around a bit to coat them in the fat. Roast for an hour until crispy, turning over every now and then.
Towards the end of cooking the chicken & potatoes fry the onions and carrots in butter until soft, then add the mushrooms, turn up the heat and fry for until they've released most of their moisture. Add a little more butter and the flour before stirring through the chicken juices and the wine from the roast chicken.