On 11 June, 14:05, "Recliner" wrote:

All six runways were built, but when jets arrived, three were closed,
leaving space for a much larger central terminal complex. You can still
make out vestiges of the old runways in aerial shots of Heathrow (eg,
one ran under what is now terminal 3's remote pier).

The two east/west runways were lengthened for the jets, which have much
higher take-off and landing speeds. Runway 23 finally closed in 2005,
but was seldom used in the last few years before then. It was only used
when there were strong cross winds. It's now mainly used as a taxiway,
though the southern end is also used for T4 stands.

L and R do indeed mean the left and right-hand parallel runways of a
pair (the few triple parallel runways denote the central one with a C).

The number is the magnetic compass heading. Thus, 27L is also 09R, and
27R is also 09L. These are, of course, east-west runways, which are the
typical direction in the UK because of the prevailing winds (you rarely
see a north-south runway here). *The numbers are occasionally revised as
the magnetic compass drifts.

That all makes sense, but when I look at Gatwick something confuses
me. It seems to have a second runway, 08L and 26R, to the North of
the main one. I thought Gatwick only had one runway. This one is
rather short, and the markings on it are slightly different to those
on the main runway. What is this used for?