Say again ?
Throw a die :
Ok so maybe my attempt at humour (yes with an O) went over your head.
The fact that you mention Avianca means that you are aware of the problems associated with the english language and the (at the time) lack of a standardized (with a Z) phrase from the ATC and Pilot sides.
Bearing that in mind, any airline where the predominate first language is not English and most airline crew who are native (ICAO 6) speakers but not regulars to LHR, both have the potential to misunderstand a phrase that is contradictory. NO DELAY means no delay, (great skippa looks like it is straight in to Heathrow eh what!), minimum delay means expect some delay (golly gov better look that up to see how much delayand add some fuel!)
So unless UK ATC comes up with a better phrase , as foreign carriers increase service, you can expect more problems with low fuel.
Also I am not sure you completely understand the range of potential problems that can put pilots into the low fuel state. You seem to think that everything should run like a train schedule (well a Japanese Train anyway). Well amazingly it does 999 out of 1000. As pilots though we are faced with more potential for unexpected higher burn than even a few years ago. While weather and en-route forecasting is accurate most of the time, it is still off once in awhile. It happens more over the pacific and North Pole routes than over Europe for example. Those pesky jetstreams can move fast. Also crowded skies mean optimum flight levels are often taken. Fuel temp issues often mean going very fast or descending both of which eat into contingency fuel. Even today you can be asked to do 360 s over India or Pakistan. You do one 360 and you loose a lot of fuel. Unexpected enroute comm failures (ex. loosing CPDLC) often mean re-routing and loss of contingency, and these are just a few reasons.
Oh and here is another pet peeve. Not all busy airports use holding when traffic backs up. I know that airspace is at a premium over LHR. However a long slow circuit at higher altitude burns far less fuel. The act of banking a heavy jet increases the thrust and therefore the fuel burn as compared to straight and level long downwind vectors over the same time period. I would much rather a long descending vector back a 250kts then a 6 turn hold at 220kts.
In conclusion, I sympathise with ATCers as your job is not getting any easier. However all I ask in return Mr. Dice is that you get down off your high horse and consider those of us who have been strapped in the aluminum tube battling our way across the world all night !!
On other thing VHHH has gone to minimum spacing on approaches now.
FLEX: Nicely put.
Five Green out ! (I am definitely laying off the Red Wine from now on!!)