Isn’t the safety point here that crews should not make promises that could degrade safety? This in turn raises the question as to what ‘Expedite’ actually means; do ATC and crews have the same understanding. The only examples of ‘Expedite’ that I could find in CAP 413 relate to climb/descent which implies the best possible rate – a characteristic of aircraft performance and the safety environment. If this interpretation is applied to ground operations, then the main characteristic is crew judgement as to what is safe, to remain within aircraft limits and the ground situation; the latter depends on the airfield / runway. This line of thought suggest that requests to ‘Expedite’ at LCY either in the air, taxing, or during take off should be used with great caution, and possibly not at all as the human desire to help others often overcomes the self control required for safety.
The thread started, if I interpret it correctly, with an observation of differences in taxing speed; that alone should raise safety concerns especially at LCY. Care must be taken not to degrade the good safety record at a difficult airport either by hasty crew action or less thoughtful ATC requests.
“We all try to help everyone else to have our own accident.”