Take back control of what exactly?
Do the recent decisions by Dyson, Nissan and Honda (none of which were due to Brexit, but due to market circumstances) not ably demonstrate that governments have little control over industry .
Didn't the crash of 2008 show that governments have minimal control and options around fiscal policy and the movement of capital or for that matter the economy.
Oh and every trade deal involves both parties giving up a bit of sovereignty, as both need to agree to standards etc over with the other party has control.
Or did you mean migration where we have always had control over non-eu migration yet have failed to control it effectively
https://news.sky.com/story/non-eu-migration-to-uk-highest-for-14-years-but-eu-migration-slows-11566853 &
https://fullfact.org/immigration/eu-migration-and-uk/