The following is based on my own observation so may not be a true representation but gives an insight to what I have seen the last 3 months I've been in England.

Cleanliness;
Yes, cars are much cleaner here. It might be a combination of weather and bad roads that conspire against Irish cars but cars are in much better nick here. The amount of places you can get your car cleaned is also a lot different in England, yes every garage and street corner has the local car wash but so do the supermarkets. I've seen one in limerick, waterless wash facility in childers road but this pales in comparison to what I say in Saintsbury last week. As I go out of the car I could see 15-20 people (all one company) with car wash trolleys advertising car washes as you shop (£4/5). Simple wash with mitt and dry (I guess) without the car leaving the parking space. Truly the lazymans way to get a car washed, no fuss and no waiting

Swirls
This is where it gets interesting, with the amount of possibilities for cars to be washed incorrectly in England I feel they may be more sustainable to swirl creating (wash the car every Sunday routine). It doesn't help that that it much sunnier so more obvious to see swirls. Maybe the poor Irish weather and less frequent washing is actually helping the paintwork rather than damaging it