OK, the definative answer from my perspective is that a 2003 2.0L JTS has 4 sensors. 2 pre cat which are 5 wire wide band Bosch LSU4 sensors and the 2 post cat are 4 wire standard sensors. The wide band sensors were £88 each which hurt. Bosch part number 0258007156, I fitted them last weekend and all is OK. Found best place to get them from is
www.justlambda.com, who delivered in 24 hours. Only issue was that the front 5 wire sensors were hardwired into the car at the sensor plug, so ended up splicing the new sensors into the old sensor wire. This meant I could have saved about £20 per sensor if I'd know as I could have purchased a generic LSU4 rather than the specific part number for the applicaion (which has the correct plug and wire length).