CIM, technically if the A/C leaves the ATZ it is only then subject to FIS and could be in conflict with traffic not talking to Cranfield tower. So be aware.
Also, 3 deg glideslope is 3 x distance from threshold so as the base to final turn is at 5-600' you should be at 2 miles. If you are at 800' on final you would be at 3 miles
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