Research shows that the aux belt roller for Honda is £10 cheaper than the Jag. Same part number /Same supplier /same maker here in UK. This is for XK8 96-02 only.
Search " Aux Belt Idler Pulley fits HONDA CR-V RD4 2.0 01 to 07 "
The Honda item is ebay ref 233873940247 at £19
The Jag ref is 234054772669 at £29.

The width of the item shows slightly different as for the Honda they measure the flat bit while for the Jag its the total width ...part numbers identical thro variious makers.