Likewise, would agree with RUDAS.
Oddly enough, had to do this (more or less) one time only, arriving at LHR.
ATC asked us to remain at FL370 while holding at LOGAN, due to an ATC radio problem with another aircraft.
Now the hold at that time at LOGAN was depicted at 'max 210KIAS'.
As this was clearly not possible at out altitude, so informed the controller.
He asked 'why not?'
Maybe if fam flights could be done on a more regular basis...or indeed done at all, the ATC folks would have a better understanding of aircraft performance.
After this ATC 'problem' with another aircraft was solved, descent was begun in the holding pattern at LOGAN.
Then...onwards to LAM and more holding.
The ATIS was reporting 4km...but I began to wonder.
Asked the F/E to monitor LHR ground, and sure enough, they were in the process of switching to LVP procedures, all the while the ATIS still indicated 4km.
Made a beeline for LGW...and was the first in the very long line that followed.
That particular day...LHR ATC was not as sharp as desired...or usually expected.