Hello,
please tell me where of the chassis of Mk V we can identify the chassis number.
Kind regards
I believe it should be in the same position as on the MK IV - which is on the lower front chassis arm above the leaf spring on the right hand side of the engine when looking towards the radiator. It took some time to find mine as it was coated with underseal and dirt. The number is stamped into the metalwork.
On Mark V it is stamped on the bracket for mounting a Left Hand Drive brake master cylinder, regardless of whether the car is LHD or RHD.
Hi,
Yes, exactly and as I think his car is LHD just like yours, so the easiest way to locate it , is to look for that brake master cylinder and then. clean the horizontal top surface of that bracket.
Here’s a photo of mine taken in 2007:
Cheers!
I stand corrected, but I seem to recall crawling under one of the first MK V cars off the production line at a classic car meeting to be shown the chassis number when I was searching for mine on my MK IV. I did take a photograph of it (which I’m trying to find) being on the front chassis arm. Is it then that there are 2 positions for the number, or did at the end of 1948/49 the early MK V’s share the chassis stamp location with the MK IV before Jaguar opted for the easier position on the bracket in later production? Alternatively I must be having a senior moment or I’ve been dreaming!!
Certainly there was (according to Jaguar Heritage) a change in the Identification Plate between the very early MK V’s (which was initially the same as on the MK IV) and the later MK V’s - so they could well have had the different chassis number locations depending on the year build.
This is the information I have:
TYPE A.4 was 3½ x 4″ brass for the Mk IV and very early Mk V
TYPE B.1 was 6½ x 4¼” brass for the Mk V, and very early XK 120
David, you are correct that Mark V has the chassis number stamped in both places, but on the outboard side of the left front chassis rail where the bumper bracket is attached it is usually so faint that it can pass undetected for years; in fact can you imagine anyone owning a Mark V since 1969 and only becoming aware of this second spot after reading about it in 1999 on the jag-lovers and wire brushing the area to find it? Now who could that be? 
You are also correct that the ID plate changed once or twice.
Early cars have a separate little plate for the gearbox number.
David,
Your photo of CHASSIS PLATE from 637102 is of course from a May 1948 LHD Mark IV DHC albeit your photo caption suggests otherwise…
What you call the TYPE B.1 plate, is as used from the very first XK120s, and same age Mark V albeit I haven’t narrowed down the demarcation date, but as you say 6½ x 4¼” brass in a horizontal format, and indeed ALL these plates are Nickel Plated, albeit most end up with Nickel polished off appearing to be just brass…
See below, they don’t get much earlier for XK120, and although seemingly brass, you can still see a lot of the original Nickel plating, especially around the now uncovered rivet holes…
Got me checking my records as to exactly when the change was made from the vertical format 3½ x 4″ brass plates to the horizontal 6½ x 4¼” nickel-plated brass plates for the Mk V …
Best I can do is it happened sometime June-July-August 1949, based on 620275 of 31 May 1949 being the latest example I can find of the smaller vertical plate, with 520274 of 5 Sept 1949 being the earliest example found of the larger horizontal format plate.
I assume changeover happened at same time for LHD and RHD regardless of Engine and Body…
Thanks Rob - nice to know I wasn’t dreaming about being shown a number under a car !!
Yes Roger - I clicked on the wrong photo to upload on my post. This should have been the picture I was sent as an example of the MK V Plate
I slight improvement now… 620342 dom 13 June 1949 has the earlier smaller vertical brass plate…
As does 520117 of 20 July 1949, and indeed 520106 of 19 July, albeit I dont have good photos.
So demarcation point is now 20 July 1949 to 5 Sept 1949 in case anyone interested has access to any cars built during this period. I know its an inconsequential issue, but what the heck… 
Thank you all the respondents to my question.
Kind regards