Here's another thought!
What do the chart symbols really mean?
The second busiest airfield in Scotland - in terms of based privately-owned aircraft - is East Fortune, south east of Edinburgh. There are c50 weightshift microlights there, but its chart symbol is just a circle with an M inside it.
At Strathaven, we have 20-odd microlights and a few GA types. We are also a circle with an M inside it.
Farmers fields with one Cessna, or one microlight, also get a circle with - or without - an M.
Yet Cumbernauld Airport - with no movements worth talking about after 5pm - has an ATZ, so would appear to be busy, busy!
SEE and avoid!