The 2 likely causes for failure are structural integrity (or lack thereof) and jagged edges.
The former is any structural member weakened by corrosion and includes the main chassis and may be taken to include the sills and door pillars (especially if seatbelts have been retro-fitted).
Most body panels are not treated as the main structure, since the bodywork of the LD10 is separate from the chassis. If seatbelts have been retro-fitted, any part of the bodywork within 12" of the attachment points will be classified as structural (which probably includes sills and door pillars).
If there is any chance of the bodywork being loose it will fail on account of possible danger to other road users.
The wooden floor panels may be counted as structure and should be securely fastened and show no signs of rot. This is especially important for the front (4) boards which retain the front seats - the (2) boards under the rear seat will probably not be checked.
Jagged edges caused by rusted wings or any part of the car that might represent a danger to other road users will fail. This means the bumpers must be fitted - since protruding bumper irons would represent such a danger, but those pointed overriders are fine. Covering jagged edges with duct tape, altho not aesthetically pleasing, will pass.
Only one brake light is necessary (altho all will be tested), which allows for installation of a reverse light with clear lens as the second rear light. Brake lights must be red and not faded or 'cloudy' - the standard rear lights on the LD10 will pass easily provided the glass is clean.
If you have fitted a reversing light, this is not subject to testing, nor are foglights, but any indicators or hazard lights that have been retro-fitted are all testable. All number plate lights must work.
Indicators can be red, or orange, and may be incorporated into the stop lights. They must flash between 60 and 120 times per minute.
The headlamp main beam image may be tested as may dipped beams, to ensure they don't dazzle other drivers, and any damage to the headlamp reflector which might affect the light will almost certainly fail.
The dipping behavior on both the Briggs LD10 (both headlamps off, passlamp on) and the Barker (both headlamps off, passlamp in N/S headlamp on) are part of the design and should not fail the test. However, due to unfamiliarity with the car, some testers may mistakenly think the Barker (in particular) has a failed O/S bulb. The majority of cars have been fitted with changes to the headlamp wiring to avoid this misunderstanding.
Any light will fail if white light is escaping (eg. a crack or hole in the glass), as will lights that flicker or are adversely affected by the simultaneous operation of other lights.
Just over 3" of free play at the steering wheel is permitted, but no structural damage to the wheel, or surface cracks or damage liable to catch on a driver's hand.
The kingpins are allowed some play (approx. 1/16").
No free play is permitted on any joint or swivel and all rubber bushes must be sound. This includes the anti-roll bar (if fitted) and may be the reason some owners have removed the anti-roll bar from vehicles.
Also check the shock absorbers are not leaking and work correctly and that the springs are not cracked or damaged.
Any splits, tears, cuts or lumps in the tires will fail, altho some surface crazing is permitted. The distinction between crazing and split is made at 1" length and deep enough to reach the ply or cords.
There must also be a minimum of 1/16" tread across 75% of the width of all tires, with the exception of the spare wheel, which is not tested.
Smooth, torn or missing pedal rubbers are the most likely cause of test failure as are handbrakes with excessive travel, or failing to lock in position.
Brakes must lock before the pedal reaches the floor, or the handbrake reaches the end of travel.
Rust may be a cause for concern, but worn or missing parts of the linkage is almost certainly a fail. Anything less than 1/16" of brake lining will also fail.
The most likely cause of failure is extreme rust causing the exhaust to be loose, or missing/damaged securing brackets.
Small pinholes are likely to pass, tho larger holes, especially prior to the last silencer box, may not.
Note that any missing exhaust mountings are a valid reason for failing the test, but most testers will not be aware of the exhaust mounting to the rear of the starter motor, which, for the majority of cars, will either be broken or missing.
The LD10 is not subject to emissions tests, but excessive smoking may still be cause for a test failure.
Only the rear-view mirror is subject to testing, and minor damage to the glass will still pass, provided it does not seriously impair rear vision.
A damaged windscreen only fails if the damaged area exceeds a 3/8" diameter circle in the 12" wide swept area directly in front of the driver. Outside this, but still in the swept area, the largest damaged area must not exceed approx. 1.1/2" and beyond the swept area, only damage that weakens the structural integrity of the windscreen is considered a failure.
The swept area must provide the driver with a clear view of both sides of the road, which probably means both wipers must be working on the LD10. The wiper blades must be sound or will fail, but any retro-fitted rear wipers are not tested.
Note that it is mandatory for working windscreen washers to be fitted to the LD10, despite these not being original equipment. This was the only automotive legislation to be retrospectively applied.
There must be one at the front, and one at the rear (with the same number), black, with white or silver lettering. The plates must be vertical, easily visible and clearly legible. Digits must be 3.1/2" high grouped as numbers and letters, with a uniform gap between digits and twice the gap between the two groups.
If hazard lights have been retro-fitted, these must have a visual or audible warning if on. Indication for rear fog lights, reversing lights (if not automatically activated) and indicators (if the trafficators have been disabled or removed) are also mandatory. Note also the previous comments (under lights).
There is no requirement for testing of retro-fitted seatbelts, but frayed or damaged webbing on seatbelts might be cause for a failure if the tester is unfamiliar with the car. Note the comments on structural integrity (under bodywork) however.
Whilst any retro-fitted rear wipers are not tested, it is mandatory for working windscreen washers to be fitted to the LD10, despite these not being original equipment.
If the car is leaking fuel from any point (the fuel reserve changeover is worth checking), this will lead to failure.
Mixing crossply and radial tires, incorrect wheel nuts, obscuring the rear window or an unsecured load (eg. spare wheel) in the trunk will also fail.
An excessively dirty car may also fail, but if you care so little for your LD10 it may be time to consider selling it to someone who will look after it properly.