There was a case many years ago (late '70s I think) of a Navajo departing Gatwick VFR. He was assigned a heading (about 020 deg I think though I may be wrong) to leave the CTR to the north then he was (apparently) forgotten, so after leaving the Gatwick CTR, he entered the Heathrow CTR still on an assigned heading.
Gatwick did not at that time, have their CTR boundary marked on their video maps.
As far as I recall, it was decided that it was the pilot's fault; he should have known where he was and requested clearance to enter the Heathrow CTR.
And the point is...? "ROCAS" should never be required?
2 s