TC ATCO,
What would be useful is if the twr had mode S readout on their ATM, then we wouldn't have to phone them to tell them an a/c isn't flying the assigned speed and to ask it to reduce/increase accordingly.
But then we'd have to phone you to find out what the assigned speed was, and what to do about it outside of 4DME.
Talkdown,
Send the front one (the perpetrator!) around then!
Some of us do that, unless it's a wake turbulence infringement.