Why do some Cross-Country Rail Services have a "9" headcode?

Question

The leading "9" now denotes international trains (Eurostars), but also seems to appear on several CrossCountry (Virgin) services. Is this "standard practise", or do they get changed to a "9" if there is a significant change in the stock or timing - maybe to avoid a clash of headcodes, or to bring the signallers attention to something like a stock change from the "normal" allocation?

Answer 1

The theory is that by running them as Class 9 instead of Class 1, they "stand out more" to the signallers, aiding regulating decisions.

Or, to put it another way, Virgin want their trains (which undertake incredibly long runs in some cases) to get priority over shorter distance ones, even if they're running late.

Answer 2

To shove off the local routes and be given priority