You have indeed correctly identified the oil pressure sensor and it is that whole silver round cylinder that screws into the tubular adaptor.
I had the same problem on my Zetec and got a new sensor from Merlin Motorsport. Demon Tweeks are slightly cheaper but Merlin have a bigger range and were more helpful.
Can't be sure the Zetec sensor is exactly the same spec the same as the Duratec but give Merlin a call. Mine was a VDO and yours looks very similar but there are thread variations.
Also variations on the earthing. Common ground if only 1 wire. You can also have a type with a second wire to a warning light but I think yours is the single wire, common ground with no warning light.
2 caveats
1. Use a good thread sealant as these taper threads can be a bugger if they start to weep.
2. On the Zetec, my problem actually turned out to be 2 fold. There is a pressure relief valve and mine was intermittently sticking which could allow very high oil pressures at higher revs so beware and keep your eye on the pressure even after you change the sensor.
Easy enough to get at and I think it has a VDO part number on it to identify.
