IIRC 123.45 used to be a Bristow's company frequency. In fact there are a significant number of companies which have their 'own' frequencies - part of the reason that 360 and then 720 channels were not enough.
And of course on the horizon the potential requirement to change to 8.33 - unless of course the OFCOM proposals mean a lot of allocated frequencies are returned.... which might open things up quite a lot!