Most ISP's in the U.K. hide such agreed consent deep within their Terms and Conditions (T&C). Because ISP's force their users to sign on the dotted line, which implies the user agrees with that ISP's T&C, even though most users will never read their ISP's T&C Making their users give their consent by the back door in this manner implies that the user has given their consent which in turn is a green light to ISP's to put Traffic Management practices into practice.
I strongly believe this method of forced consent is illegal. Thereby Traffic Management, and all other such activities that interfere with a user generated Internet data stream is illegal by extension.
In many other countries this sort of thing is being played out in courts. It is being mentioned in government circles and many other such places. Net Neutrality (the process of none interference) is a hot potato.
I do not know of any such being played out in the U.K. even though many ISP's routinely interfere or intercept user generated data streams. There has been much furore about a company called Phorm and the fact that BT conducted trials using software from this company using 18,000 of their user accounts in the process. This software intercepts a user generated Internet data stream then uses this data to inject advertisements into a web page that user uses. All this is done without the user or indeed the web site owners knowing it has been done. More on this, and quite probably a better explanation, can be found here.
My own ISP, Karoo, intercepts all its user generated Internet data streams and employs what it calls 'Performance management' which is just other name for Traffic management. it intercepts user generated Internet data streams then applies some logic to it at the end of that is slows the data stream down. They have claimed this is "industry practice` which is a blatant lie but it is used by a lot of ISP's in the U.K. The very fact that they intercept user generated Internet data stream is I believe against the spirit, if not in legal terms, of the Regulation of Investigatory Powers Act 2000 (RIPA)
As this sort of thing is being played out in courts all over the world I have taken it upon myself to fight the good fight in the U.K. to get all such interceptions and all interruptions of user generated Internet data streams abolished. I shall take the fight wherever it leads me against anyone who wants to shot me down.