Obviously people being stranded in the wrong country overnight is undesirable, but really the scheduling of these flights (particularly some German destinations served by a major UK airline) must be called into question. If certain flights are frequently requesting priority, something must be wrong somewhere.
Asking for priority around 2000 hours outbound is simply not fair on the other airlines. Why should they be penalised for one flight that cannot suffer some schedule shift that happens frequently particularly at busy airports? It's time that things changed rather than putting pressure on ATC and their own crews.