> In order to make the card work in BSD you need to ifconfig the card in
> RISC OS before booting BSD. This is because the driver does not do
> something required to enable interrupts for the card. The ifconfig in
> RISC OS makes sure this initialisation happens.

That was the problem!. I've added a line to !BtRiscBSD.preboot to
ifconfig the card, and presto, it works.
 
Thanks for all your help and suggestions.

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