On the...ford underpinnings.
X type had a modified Mondeo platform.
The above is partly correct as mentioned in my post - the X-Type shared a platform with the 1993-2007 Mondeo, the petrol X-Type used a version of the Ford Duratec unit, diesel X-Type used the Ford Duratorque unit.
The S-Type shared a platform with the Lincoln LS and the Thunderbird. Your comment about Ford engines is ill-informed, Jaguar only developed one engine for the S-Type and that was the V8 (manufactured at Ford's plant in Bridgend). The diesel S-Type used the well proven 2.7 litre (Lion) unit developed by Ford and built at Dagenham (used also by PSA). The petrol V6 used was Ford's Duratec, another well-proven unit good enough to be used by Aston Martin as a V12.
Rk.