Bernie
I am familiar with the S3 but have no idea what a V5 is. In any event, guesses follow:
The VIN (Vehicle Identification Number) is located in three locations:
(A) on a metal tab (about 3/4" by 1.5") inserted between the windshield and the left A-Pillar inside the cabin (about eye level when seated in the LHD driver's seat); it's visible/readable from the outside of the car.
(B) stamped into the body shell immediately above the point at which the engine left side-frame attaches to the fire wall (very near the heater box)
(C) on a stamped metal plate (about 2x8 inches) affixed to the fire wall just offset from the center-line of the car (see attached photo (**)). This plate will also display the numbers for the engine, transmission, and body.
Depending on the YOM, the VIN will start with a UC (1971-72), UD (1973) or UE (1974), then 1S. The next digit will be a 2 (if an export OTS) or a 7 (if an export 2+2) and then followed by the 4-digit sequence-of-build number (mine is UC1S20954). If your Jag was built with an automatic transmission, the VIN will have a suffix of "BW" (for Borg Warner).
The Engine Nr (to confirm the one stamped as above) is stamped into the the block in the Vee on a flat surface above the join between engine and trans just visible looking down into the transmission tunnel.
The Trans Nr is on the transmission but I can't recall where exactly on the manual nor automatic.
The Body Nr is stamped into the body shell on the vertical vehicle face between the bumperettes and below the rear bumper. To access it you need to remove the rear license plate (no big deal) and the brushed aluminum plinth behind the plate (PITA to remove (*)). Part number for this plinth is BD37649 which fits the US style license plate size. You can replace it with BD38883 which accommodates the UK size/style plate.
Hope this helps -- Craig
(*) the plinth is held in place with 4x screws along its bottom and 2x rivets, one each in the upper corners.
The much wider UK-style plinth is secured by the same 2x rivets in the upper corners but 7x rivets along the bottom face. This change, if you choose to do it, will also require a different mounting bracket for the license plate. The single US style bracket (BD35672 - held in place with 6x rivets) is replaced by 2x small wide-spread UK-only brackets (RH: BD38880 + LH: BD38881 -- each held in place with 2x rivets)
(**) the 8" wide plate is visible just to the right of the bonnet safety latch. The VIN is stamped either above or below the opening for the pedal box, which is below and (in the photo) left of the heater box opening.