Light signals to aircraft

[hugh flung_dung]

I have always (well, for nearly forty years) understood that flashing white meant "land at this airfield", flashing green effectively meant "continue in the circuit" and that solid green meant "clear to land". Today, a student pointed-out that CAP637 says that flashing white means "Land here on receipt of steady green and await further instructions" and that flashing green means "Return to aerodrome, await landing clearance".
Have I been wrong for all those years or is there a wobble in CAP637? If the CAP is correct, what's the difference between flashing white and flashing green?

HFD

[Whopity]

CAP637 is out of date in any event. The light signals in SERA are:
Series of white flashes
(Air) Land at this aerodrome and proceed to apron (*)
(Ground) Return to starting point on the aerodrome

Series of green flashes
(Air) Return for landing (*)
(Ground) Cleared to taxi

(*) Clearances to land and to taxi will be given in due course.

[hugh flung_dung]

You are, of course, correct about SERA but the PPL exams are frozen in 2014 so we need to point-out differences between knowledge for exams and for our brave new world :-( In this case there's no substantial difference, but I'm still struggling with the difference between "land at this aerodrome" and "return for landing" if the latter doesn't mean what I said earlier.

HFD