I don't remember the last time I saw Stansted or Essex listed on the CFMU regulation list when it wasn't for fog or wip or an incident.
I don't think that it is a reguar place where flow is applied to the airspace.
Even Heathrow is rarely regulated for the whole day.
If one calls for a transit and is told to standby and the controller forgetts about you while you fly round the zone then most definitely file it as being denied a transit you could also quite rightly report that the controller did not get back to you in a reasonable time which they are rquired to do even if it is simply to tell you there is no chance of a transit.
Regards,
DFC