Sounds like a shrewd move. You can be too successful in bringing numbers in. Also allows a vetting of those attending to keep the potential trouble makers out before they arrive. Mike is quite able to turf them off his land but simpler if they are not present in the first place.
I am not so sure this is not going to be a more common part of organising events now. Unless your tooled up to do a National or something, where numbers can be catered for and the emphasis seems slightly different, predicted and groomed numbers just make for a much simpler life then catering for those attaching themselves to something having not understood quite what it is all about and who then create issues when things do not suit them or simply choose to confront a consensus of activity.
Heinkel 175, Vellam Isetta, Messerschmitts KR 175, 200s, 201, TG500, Scootacars, Frisky, Peels, Bamby, AC Mk12C and Type 70, Velorex.
MG ZB Varitone, Wolseley '4/136', Borgwards, Saab 96s, Bellamy trials, Alfa Duetto, , Isuzi Trooper, Citroen BX 14E, 16TRS Auto, 17TZD Est and Sal, GTI 16V, 1960 Bole