Well in an incredibly busy airfield like Shoreham, if you blast from standing start to 1100 agl by the end of the runway, without screamimg from the rooftops that you are intending to do that, and all joiners beware, then you are an idiot.
Although that advice makes sense at airfields where OHJ or crosswind joins are used, I have never ever seen it written down anywhere.
You fly Vx (plus the associated flap settings) until reaching 200', then reconfigure and fly Vy until reaching circuit altitude. Although you might, depending on the aircraft, adopt a different climb speed when above 1000'. That's the only take-off profile for which you have actual performance data in your average spamcan. And that's regardless of the length of the runway, circuit altitude or your actual ROC.
In fact, I think you could argue that the "idiot" in this case was the person crossing the upwind end of the runway, while another aircraft was taking off.
(Note: I'm not at all familiar with this accident or the circumstances in general. I just think it's the person performing the crosswind join who should give way to the aircraft taking off, not the other way around. And yes, I've been in this exact situation: Climbing out on upwind, at about 700' AGL, when an aircraft crossed directly in front of me at about 30 feet distance, same level. I can still recall the whites in their eyes.)