The plug thread is fine, just a few wisps of alloy in it. I did think about thread-sealing it in, but the way it came out so easily (and wiggled in the hole too) suggests that won't be an option.

Just had the RAC van come, he offered to tow it to the garage, I point-blank refused. He showed me on the laptop "max 10 miles at 30mph with solid bar", I said if he'd just spent £1700 having the gearbox sorted, would he risk it?

He phoned through for the flat bed