Not sure if this is applicable to you but i was going to add it anay way and then found it on another forum
MODE SWITCH
In High range press the mode switch to select
Sport mode (the S information light on the
instrument panel will illuminate).
In Low range press the mode switch to select
Manual mode (the M manual information
light will illuminate).
Press the switch a second time to return the
gearbox to normal operation.
Sport mode
With Sport mode selected, the gearbox is
more responsive to accelerator pedal
movement - downshifts occur earlier and
upshifts are delayed to make optimum use of
the engines power while accelerating. Select
Sport when increased acceleration is
required, or when negotiating long inclines or
twisting roads. Note that driving in Sport
mode will increase fuel consumption.
Manual mode
In Low range, with Manual mode selected,
the automatic transmission functions as a
manual gearbox requiring the driver to move
the selector lever manually to change gear
(D = 4th gear). Manual mode will provide
maximum vehicle control and engine braking -ideal
for use in severe off-road conditions.
Note that kick-down is disabled and that
automatic downshifts will only occur to
prevent the engine from stalling.
NOTE: Switching off the engine or using the
transfer gearbox will automatically cancel
Sport or Manual mode.
Very Good info, as i know my dad uses his M mode in his 4.0 disco 2 quite a lot