mail.tlca.uk has no CNAME records.
Question and response
Question
dig mail.tlca.uk. NS
Answer
The response has no answer records.
Authority
tlca.uk. 9844 SOA ns1.linode.com. thestandfordarms.intel.com. 2021000056 14400 14400 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0