For
your information, all SID's have a common lettering system. Departures
from 26L have the prefix "M" and those
from 08R have "P". Of course, when 26R
is rarely brought into operation it has the prefix "V"
and 08L has the prefix "W"
Also,
it is advisable to note that all departures wishing to enter the
LTMA (London Terminal Airspace) are required to file a valid SID
before departure to ensure that there flight will be accepted
by London Control