1997 Jaguar XJ6 replacing engine belts

I'm trying to replace both engine belts, as one has shredded off (serpentine) and the v-belt to the P/S unit is in front of the Serpentine belt. how do you get the idler pulley loose to remove the drive belt to the P/S unit ? It's not a spring loaded idler pulley as I'm used to. Thanks in advance