Doesn't sound like your brother is a particularly good driver .... The ST gears are very precise and I find it hard to imagine selecting 1st gear instead of 3rd, I don't think I have even come close. Take him off the insurance before you need to claim for a new gearbox or worse, engine !!
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Escort 1.6GLE, Escort 1.3, Fiesta 1.3, Fiesta ST!