Tech Bulletin - Shedder Plate PHL000010 (75 / ZT Diesel, All Models)
In 2003, MG Rover released this part to fix the issue of contamination of the MAF Sensor during extreme spray / rain conditions.
A copy of the Tech Bulletin is available to view here: Tech Bulletin - Shedder Plate
We'd recommend fitting this to any 75 or ZT (diesel only) that spends a lot of time on motorways, as that's when contamination is most likely to occur.