We used to leave our van overnight outside our house, which was on quite a busy road for a night or two when loading up. We never had any problem, the police didn't seem to bother - although they did pass by several times daily - and the only time anyone made any comment was when we had to leave it outside for several days during the 'petrol strike'. As it happens this did us a favour anyway because we put a for sale notice in, and sold it to a passer-by!
I'm not saying this would be the same wherever you live, best to check, perhaps with your local bobbies!