Colin, undo the two bolts holding the caliper to the caliper mounting bracket. You need to use two spanners when doing this, one to hold the sliding pin I think its 15mm, and the other to undo the actual bolt 13mm. Carefully ease the caliper away, take care as they have a rigid brake pipe but there is plenty of movement but don't go berserk! Lift out the pads and away you go. Also use copper ease on re-assembly it will help to stop brake squeel.
Phil