Mr Angry, in response to "how about the fact you get a basic salary or have you forgot about that minor point?" - Going by the same logic, why do companies all over the world have standby pay, sector pay, per-diems, overnight pay ...etc...etc? Basic pay makes up a portion of your overall pay with all the additional duty pay making up the rest of your overall package.
Thank you for your replies guys. Any more details of standby conditions from anyone else would be much appreciated. Thanks.