Well everywhere has its twats, here's just the same.
But in terms of policing they are mostly are pretty chill. I have had two totally polarising encounters with the police in my life though. The second one first..
I got arrest walking back from a gig smoking a spliff. I threw it to the floor as soon as I saw the officers and they ran up to me and grabbed my arm. They then walked me, I kid you not, to the station which was about 1 minute around the corner. The whole time I just walked next to them talking and when I got to the station the custody sergeant made me a cup of tea and let me chill in the custody suite as the cells were filled with all the Friday night drunks. I ended up in an interview, said no comment throughout, they offered me a police caution which I rejected and then they let me go. All within 3 hours. Two months later I got a 'no further action' letter in the mail. Not bad considering I was actually breaking the law.
Another time I was taking my sister to a specialist orthodontist in London. On the way I wanted to stop at Liverpool Street station and grab a copy of the new LMA Manager game. So we head to a Virgin store and buy the game. So I should explain first that Liverpool Street is in the City Of London or the "Square Mile" so is policed by the City of London Police. I'm from London but at that time very rarely went to the Square Mile so was used to seeing blue Metropolitan police uniforms. So my sister and I come out of the shop and walk passed this kind of extravagantly dressed officer and I smile and chuckle a little.
In that the officer approaches my sister and I and asks what we're laughing at. I'm 16 at the time and just sort of thought he was joking. So came back with, what I thought was hilarious banter, "your hat my fair king" and bowed a bit. He looks at me in the most evil way and grabs me and slams me against a shop window. He tells my 13 year old sister to stand aside. He then gets on the radio and within probably 30 seconds 5-6 plain clothes police are there. I just kept saying I was joking but he just ignored every word I said until the other officers got there.
Then, one of the officers puts her hands on my sister. At that moment I felt completely hopeless to help her from what I thought was a potential violent situation. Probably the first my sister had ever encountered in her life. I thought to remain calm so not to provoke them or give them good reason to get more physical but I was burning inside, the anger was overwhelming, something I had never felt before. I then started trying to appeal to female officers, saying how my sister is only 13 there is no need to put your hands on her she will comply and the officer holding me kept telling me to be quiet. In what was my second stupid mistake, I quip back "I have the right to remain silent but I don't fucking have to" or something to that effect but before I can even finish he slams me to the floor. At this point I am screaming at passers-by to watch and film, my sister is crying her eyes out screaming at me to calm down, I was calm until I was physically assaulted, and the other officers are doing nothing but standing there and every now and then talking on their radios. Then, after all this bullshit the officer laying on top of me proceeds to arrest me for the theft of the game I had just purchased! The bag the game was in had the fucking receipt in it.
SO.. a meat wagon pulls up and me, cuffed, and my sister, not cuffed get put in the seats at the back. Not in the cage, at least. The whole time the officers sits next to me holding my cuffs. At this point my smart-arse-16-year-old-self is goading him, explaining to him how I was going to sue him as soon as I leave the station and when the custody sergeant here's my story he's toast, etc. etc. and he kept replying "well you shouldn't be a thief then", which made my blood boil because that's all he would say back to me.
We get to the station I insist that my sister not leave me as I am her guardian and they agree. I tell the whole story to the custody sergeant, he seems uninterested and just goes with the story the arresting officer goes with.. until.. He asks me to empty my pockets and when I do I put my wallet on the counter and my keys. He starts looking through my wallet and see I have a debit card. He says "did you buy the game with your debit card"? I said "yes I did as it says on the receipt". In that the whole thing came crashing down. I look at the arresting officer and it was he had gone white. They take me to an interview room with my sister and we wait there for like an hour. They ask us if we want water but that's it. Then the arresting officer comes in and says we're free to go. Well now I'm thinking, you fucked up mate and I'm going to make sure you know it. I say that I want to make a complaint of assault. I try passionately to ask him why he did it and all he says is it was mistaken identity, but if I want to make a complaint I will have to wait for someone to come in and fill the form with me as he couldn't do it. We sit there for another half hour, the whole time my sister begging me to just leave it and in all honesty I just wanted to get home and play my new fucking game. So we left. I get home tell my parents and they take me back up the station to make a formal complaint. We were up there four. fucking. hours. plus travel time there and back.
After all that, 7 months later I get another 'no further action' type letter saying no action will taken against the officer due to lack of evidence. This was next to Liverpool Street station one of the most surveillanced patches of land on the planet. They'd have no doubt had the whole incident in multiple angles in HD.
But anyway, just shows there are scumbags everywhere.
Oh and sorry for the wall of text :/ but thought it a good time to share my experience with the British police.