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Err, I think you will have problems at MOT time with the latest rulez. No film applications allowed, period! is what I have heard.
And even if you think you'll be clever and get around it by removing and then putting back on afterwards, the Police can stop and book you.
Depending on the strength of tint, from a road safety point of view it's a very foolish idea. I was following such a car recently and his tail lights were barely visible.