eds123, I believe your prognosis is most likely. I found the Jag's tech bulletin on SRS which details the flash codes and restraint DTCs. Fortunately, if you have a flash code 19, it doesn't really matter what your DTCs are as they all refer back to the same points of failure which are:

1) CA114 (Connector into the control module)
2) FC117 (Steering Wheel Cassette [aka clock spring])
3) SW11/12 (Ignitor wires to steering wheel airbag)
4) FC42 (4-way connector that ignitor wires attach to behind instrument panel but i'm thinking this connector might be behind the access door to the left of the dash)
5) CR086 (I'm not sure what this is - any ideas?)

Note; there is no connector under the seat noted within this bulletin - granted this is a 2005 release of the bulletin. If anyone has something newer perhaps that information is in there.

Update:

I performed 4) which was very easy to check. The plug is on the side panel of the dash as I assumed, yet still had the airbag light, then 4) because these 2 do not require parts. #4 was a pretty lengthy tear down. Knowing what I know now, I would check 4, 2&3, and then 1. It turns out that the clockspring was my problem as well. Part number C2P14221 for an '03 S-Type from the Jaguar dealership. $199.00.

 

If he SPRAYed water under the seat probably your problem was on the yellow connector with some moist / condensation inside the contacts or short bars... If he just pour water.... then is unluckly that the water level goes up to the connectors or harness bracket level. So just disconnect battery (wait at least 30 secs.), remove yellow connectors and spray some contact cleaner and Water Displacement (WD40)inside. Water condensation inside the vehicle is your worst enemy.......

Axel