The message
from James Fidell contains these words:

I thought I'd have a go at growing celery for the first time this year,
but despite having an abundance of other vegetables from "easy to grow"
to "could be a bit tricky", not a single seed from an entire packet of
celery (Victoria F1) seed germinated. Even my celeriac (supposed to
be fairly erratic, I think) produced a reasonable number of seedlings.

Anyone have hints for improving my chances next year?

I think celery is more fussy than celeriac. Did you have them in enough
warmth?

Janet G