A horizontal wiper and its operating arm modification must not in any way partially obscure the high-level brake light found at the bottom of the rear screen, as built original equipment on your 1998 vehicle.
The annual kiss the MOT tester’s donkey exercise may well find an excuse to stubbornly object refusing to budge and fail the MOT, claiming the rear high-level brake light is partially obscured? All grist to the MOT tester’s mill and easy extra money in their pocket as any excuse to MOT fail will enable them to create extra work to maximise their income and profits.
Some annual kiss the MOT donkeys do play ball and other kiss the MOT tester’s donkeys do not play. Reminds me of the homily, Some Girls Do and some girls won’t. Racey eh?
Enjoy