You need a job offer. Then you need to apply for a work visa. Then you enroll in their tax scheme; if the UK and US have a tax treaty—which is very likely—then where you perform the work determines which country you pay your tax to. A lot of location filming is actually done in Ireland, due to lower production costs, and essentially the same scenery.

You need to contact the studios and the film industry to get yourself a visa. There was a crew from US that used to live downstairs and I used to be in touch with one of them doing the editing.
They were there for about 1.5 years and once the film got into the theatre, they left. I understood that there was recruiting firm that specialises into.
If you are serious, i will look for his number in miami and you could ask him.

I’d love to hear more about the recruiting firm.

One thing I don’t understand totally is I thought that in order for an employer to sponsor me, they have to prove that there isn’t anyone in London who could do that job. I did take a peek at what positions were lacking in the film industry there, but its all post production VFX, nothing involving production.

Thanks for all the advice everyone.

Generally speaking, job has to be advertised with preference to job-seekers from UK, then EEA, then everyone else—in that order.

New Law just went into effect of hiring extremely highly qualified individual with a certain degree is acceptable to get work permits.
I suggest you read the new legislation very carefully before you jump into it.

I am trying to remember the name of this guy so i can get you his email address. Not ringing a bell now.

By the way, the name of the moview was The Tale of Despereaux – released dec 19th, 2008 after which they either went back to Miami or found some other movies. But they left their flat.

Name of the company that produced it was framestore. Contact them in London and speak to them.