Is it illegal to videotape someone in England without their consent?

Not allways.

In Canada there is a leagel principle called "Reasonable expectation of Privacy"

So what makes it an issue is what you fim and why.

If you take Naughty pictures of Lady's with out thier knowlege, this is a problem

If you take pictures to do something else against the law, = Jail Time in addition to the other thing.

If you publish the Video without the persons in it permision, Not cool.

I use a Camera in my car all the time in case of crash and such, 100% ok as long as I do not publish the Vid in a way that Identifies the people or cars filmed.