What to do if you see an owner with a banned/illegal dog in the uk?

I know that many (if not all) UK police forces effectively ignore the Dangerous Dogs Act 1991 until something happens, then they act. Which is pathetic and makes the law meaningless. The law describes the outlawed breeds including "pit bull types" - with a vet appointed by the police having the discretionary power to decide if a dog has pit bull traits. Dogs described as "Irish Staffies" or "American Staffies" are usually pit bull types - those "breed names" are usually code that the junkie owners use instead of admitting their dog is a pit bull or part pit bull.I met with my local police in the past to discuss all of this and they were basically not interested in preventing incidents - they would only act when something happened. 

It's notable that when a dog attack is in the news the owners typically say, "it's never done anything like this before" as if that's some kind of defence. Well, it's bloody obvious that a dog that has just killed someone (usually a child) will not have done anything like that before - and it's the kind of stupid, irresponsible remark that underlines the problem with the people who keep potentially deadly pets. They describe them as "gentle giants" and "big softies" who are "brilliant with kids" until the dog turns one day and mauls someone.

If you're worried about this, read up on defensive techniques for dealing with dog attacks. All too often people try to stop maulings by going for the attacking dog's head, or kicking its body - which often makes matters worse. Instead grab its back legs firmly, lift them up and back the dog away. Even a small person will find the strength to do this, and as long as you grip the legs you're not in danger from biting. If the incident is serious you have the option of forcibly splaying the legs to break bones, or twisting them to incapacitate the dog. If you have the ability you can also swing it up over your head and slam it into the ground. In USA and other places people are able to carry firearms or CS spray, but in the UK these things are completely illegal to possess, carry or use except for police or certain other officials. 

I've used the picking-up-back-legs technique twice to stop less serious incidents. If one of my dogs (or a person) was being attacked I wouldn't hesitate to severely injure or kill the attacking dog in order to stop an attack. 

I probably would not say anything

Mind your own business, unless you have an issue with the dog, like attacking you or something. Now if this dog is by itself & not on a leash, you can report a loose dog on the street.

My immediate thought about this question was MYOB.  Sorry.    If you are really bothered, probably contact the police - but you have to be sure the dog IS a banned breed!!

It's not much different from seeing anybody doing something illegal - and you have to remember IF the dog is one of the 'banned breeds', it will probably be seized which as long as it's not out of control, would be a shame.

Blame the DEED, not the BREED.

The first port of call in the UK is a dog warden,  but if you mean a Pit Bull,  we have loads of them in the UK now although they should have a court order to allow them to be owned with regulations attached.

https://www.gov.uk/government/news/dangerous-dogs-...

How would you know it's a banned or illegal breed in the first place? 

it would usually be a male and I probably would not say anything

Contact animal control.

How about reporting it to the police or calling the RSPCA for a little advice?