ns.bbc.co.uk.[212.58.228.21] needs to be listed with the parent nameserver as a nameserver for your domain. It appears to only be listed with the authoritive and not the parent DNS server.
you can see from your parent that ns1.thny.bbc.co.uk. [212.58.240.21] [TTL=172800] [UK] ns1.thls.bbc.co.uk. [132.185.240.21] [TTL=172800] [EU] ns1.thdo.bbc.co.uk. [212.58.224.21] [TTL=172800] [UK] ns1.bbc.co.uk. [132.185.132.21] [TTL=172800] [EU]
are your name servers but from the authoritive you get ns.bbc.co.uk.[212.58.228.21] [TTL=900] ns1.thls.bbc.co.uk.[132.185.240.21] [TTL=900] ns1.thdo.bbc.co.uk.[212.58.224.21] [TTL=900] ns1.thny.bbc.co.uk.[212.58.240.21] [TTL=900]
best I can tell is ns.bbc.co.uk.[212.58.228.21] [TTL=900] should be ns1.bbc.co.uk. [132.185.132.21] [TTL=172800] [EU]
WARNING: Your SOA (Start of Authority) record states that your master (primary) name server is: ns.bbc.co.uk.. However, that server is not listed at the parent servers as one of your NS records!
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