BOAC
Bexil/Lydd/Pompi (and Bewli/Elder/Sam even for KK too) are last minute solutions when there are no more.
The upper limits at each varies depending on other traffic conditions. Bexil is normally FL190, but only to keep seperated from Tiger hold, so if Tiger isn't being used, the upper limit can be modified by ATC. I remember one morning having A/C holding at Bexil at FL150/160/180/200/220/260/270/280/310!!!
But there was no other traffic through the sector.
Lydd has no limits, and Pompi is FL180 to FL220 to keep seperated from other Lon TMA deps, and Birmingham/Stansted departures which have to achieve FL240+ by MID.
We will only 'en-route' hold at the last resort and it will only make your life slightly better, but hinder others. If we hold at Bexil, then all the LHR in's will be forced down early or vectored off route to the East to avoid the stack. Same problem with Pompi for all STN/LUT ins, and the LHR's again vectored well west.
Solve one problem, create another topic???