There is in fact a
SOA record, it's just not where you're expecting it. Let's take a look at the AUTHORITY section...keep in mind that
ns1.nservers.co.uk. is not in any way affiliated with the
nic.uk. nameservers, which are authoritative for
$ dig @ns1.nservers.co.uk. +norecurse +noall +authority vancemillerkitchensuk.co.uk SOA
co.uk. 3600 IN SOA win-k7rk0hedad1. hostmaster. 6 900 600 86400 3600
$ dig @ns1.nservers.co.uk. +norecurse +short co.uk SOA
win-k7rk0hedad1. hostmaster. 6 900 600 86400 3600
This betrays their actual configuration: they have a single
co.uk zone defined. This simplifies their configuration as they only have to maintain one file. The reason you don't get an answer section for the
SOA request is because that isn't the true top of the zone. Keep in mind that this is a terrible configuration: you should never pretend to be authoritative for domains that you're not. Don't emulate this.
SOA records are mandatory. You have to stuff something in that AUTHORITY section where it is required by RFC if you expect the rest of the internet to play nicely with you. Obviously they aren't really authoritative for
co.uk, but this at least tells other nameservers what the negative TTL should be.