muckles:
Makes me wonder if he really has a BL built Jag. 
I had 2, plus I used to help out a guy who run a restoration business, specialising in Jags, we also worked on other cars.
I saw many BL built XJ’s and XJS’s I very soon knew where to look for the problems as they almost all seemed to have the same thing go wrong and rust in the same places.
We had a XJ12 Coupe in built in the mid 70’s and a similar aged Merc Coupe. The difference you didn’t get wet and deaf because of the gaps between the pillarless windows and roof in the Merc and you didn’t crick you back trying to reach round for the seatbelts because of the long doors. The Mercedes seat belt came to meet you, really cool and showed some properly funded R&D.
My first Jag was a 1984 XJ6 4.2 from a distance it didn’t look to bad for a 10 year old car, but it had started suffering from most of the XJ Jag rust problems. At the same time my Brother had a 1983 7 series BMW, it was better specced and far better built than the Jag, the only thing the Jag had going for it really was the ride comfort.
Looking at the two cars and seeing a few of the Mercs of a similar age that used to come in, it was obvious that the XJ series had suffered from years of under development compared to the German competition.
I then bought what was known as an XJ40, the XJ6 replacement with the large square light. It was obviously Jags desperate attempt to catch up to BMW, Mercs etc. True it had all the gizzmos that you 80’s exec expected, but the problems they caused showed a serious lack of development.
Problems were. Self leveling suspension, so crap that Jag junk it. I had to replace it with a standard Spring and damper set.
The Accumulator that fed the brakes and suspension, failed and very expensive to replace.
Door Handles that broke so regularly that trying to get one from a specialist breaker was almost impossible.
The boot lid that rots, again almost impossible to get one from a breaker, so we rebuilt it with new metal.
and more computer glitches than using Windows Vista.
Don’t get me wrong I love Jags of that era and had they been allowed to be properly funded and properly managed instead of resting on their past reputation, they would have been a match for any German Executive Car.
As for the lazy workforce probably true, but considering the quality of the cars we now produce for foreign companies, compared to other Countries, including Germany, you’ve got to think that poor management had something to do with it.
Carryfast:
The XJ series 3 actually had/has a better wishbone front and at least a better lower wishbone/drive shaft IRS than the old BMW McPherson struts and semi trailing arm rear which you’d have found on a much cheaper Triumph 2.5 of the 1960’s although at least the Triumph,like the Jag,had rack and pinion steering unlike the 1950’s Ford type steering box lash up on the Mercs or the BMW’s.
the only thing the Jag had going for it really was the ride comfort.
Carryfast:
I had a BMW 3.0 and the fact is like all the rest of them the thing was rusting away at 7 years old and needed plenty of welding at that age whereas my 1984 series 3 XJ 12 hasn’t,yet,needed any which is why you won’t find many E3’s left now unlike the Jag XJ’s of the same era.
Never mentioned E3’s
Carryfast:
So you’re saying that a 1970’s-early 1980’s XJ12 wasn’t/isn’t a match for a 3.0 Litre E3 or 3.5 Litre 735 BMW of the time not forgetting that the BMW actually costed more when they were new. 
If you’re talking about performance then maybe not, but the V12 is a 5.3l compared to a 3.0l or 3.5l. But if you’re talking about development and build quality then from what I saw Yes.
Carryfast:
Put a 6.0 Litre engine and 5 speed manual box in the Jag,which mine’s got,and even a 3.5-3.8 Litre 24 valve M5 of the time or later wouldn’t even see the thing’s tail lights on an unlimited stretch of autobahn on the German heaps’ home turf.
Your Jag sounds great, but it’s modified not standard so you cannot compare with the same stuff of the era, but my argument had more to do with lack of decent R&D and build quality.
Carryfast:
But then anyone who knows anything about Jags knows that the XJ40 isn’t as good as the older ( mostly Leyland built ) XJ series 1/2/3. 
I think I pretty much covered the problems with the XJ40 which was developed during the BL era and never said it was better than the old XJ series.
For all the faults I actually really liked my Jags and I’d have another XJ as a classic car, but only if I couldn’t afford an E type, but I’m not so blinkered that I couldn’t see the limitations of them.