"According to the same survey, 30,000 of them are drawing dole.
That will cease with Brexit"
As nothing has been agreed on brexit terms and conditions yet the above statement is merely a supposition. Unlike yourself I am fully aware of the difference between fact and supposition. As Britain did not join the schengen zone the right to check passports of all arrivals and departures was always retained. Free movement only ever occurred for EU nationals, but movement was always monitored. To an extent this duty of checking was thrown on the airlines as they picked up the repatriation tab for illegal aliens. Passenger manifests have been vetted and retained for many years. Even crossing the Irish Sea random checks occur and passports frequently checked.

In conclusion I would think it perfectly obvious that far more interest is taken on those aliens arriving than those leaving and all my most recent departures from heathrow I have been photographed as well as my passport checked. The latest intensification of passport controls took effect on the 7th October 2017