I think King of Sat are wrong, they list "BBC HD" as well which is a channel that no longer exists and hasn't for some time.
Plus if STV and UTV were really there they would be transmitting in the same modulation format as ITV HD.
So just editing ITV HD's PIDs from VPID 6201 to 6501, APID 6202 to 6502 and PPID 6201 to 6501 would open STV HD instead of ITV HD and it doesn't.
I believe King of Sat are incorrect some UTV and STV data may be in the stream but not a full transport stream of all the data to enable UTV or STV to be viewed, likely just EPG data or something.