Re: why do I get "No response from server"
I am afraid that both my claims were wrong:
that the NS records in the zone were different from the ones
at the delegation point (I had picked the wrong set of NS
records from the authority section of a reply)
that mail1.ccs.bbk.ac.uk was not authoritative for lkl.ac.uk
(its not authoritative for bbk.ac.uk which the CNAME points
into, but so what)
That will teach me to post too fast (maybe). Apologies.