Hi Safetypee,
We like to keep our aircrews happy At London City, because they help US out when we are busy or have made a merry stew out of the traffic pattern with little whinging, and 10 kts difference between 180 & 190 is not enough to get worried about. So it generally is appreciated by pilots to let them stay clean longer, especially as we reduce speeds a lot earlier than other units. eg Heathrow reduce spped of a/c to 180 on the base leg turn about 20-23 miles ish. We when busy can reduce our aircraft to 180 35-40 miles out, due to lack of holding facility - but thats another thing altogether.
Im not talking about telling a pilot to fly '160 to 6 miles' and the pilot requesting 220kts, that is a different thing altogether, im talking 10-15 knots either side. Ill regularly reduce the RJs to 190 and the Fokkers to 180 because that 10 knots doesnt make much difference to the vestoring or safety of the traffic flow. If it was a problem then i wouldnt try and keep one clean they'd all be 180 or 190 or whatever. Though I do appreciate where you are coming from in your post
Alex