I phoned up ATC and apparently London Control are now implementing a procedural separation for departures. It has happened for some other aircraft recently.
What is “SCNR”?
Sorry, could not resist …
Emir, isn’t twin-envy great?
Yeah, I’m just smiling
I guess you are already satisfied with the explanation you have Peter, but for what it’s worth I have encountered this at many IFR class G airports.
Were you also routing to or near GWC?
The problem is that while they don’t need to worry about separating you in class G (aside from duty of care arguments), It is not much good for them if they have to have separation of xnm at the same altitude or yft, or a combination of xnm and yft for composite separation if you both get given a clearance (example only, I know not the procedures at Shoreham) to join CAS on track GWC climbing to FL90, because then chances are you are going to both enter controlled airspace already in a loss of separation scenario.
I have had this happen at Biggin fairly often were I have been waiting to depart with no real traffic around aside from a departure only to be told that “your clearance is on request with Thames, expect a 5 minute delay”
London Control have been used timed separation for departures since before I became an air traffic controller in 1985. I suspect that there may have been a subtle change somewhere such that this has become more apparent at Shoreham/Goodwood.