Deportation and Overstaying in United Kingdom?

Question

If someone is deported from the United Kingdom via a letter but did not leave for another 3 years, what would happen if he/she tried to leave from the UK.

Do they check for visas or leave a deportation record at the airport?

Answer 1

Na. They'd just let you out. They don't need more paperwork!

Answer 2

Immigration officers will escort you to the aircraft and wave you off, bye!