MartynSinclair – In fact we have already reported on falling demand on the Brussels route.
The latter has taken the brunt of the cuts. In addition the Brussels route is still not cleared (by the Belgian authorities) for Eurostar to operate its new Siemens trainsets. Therefore the latter are currently in service on London-Paris only.
Eurostar is running endless seat sales (the current one expires March 16) as it struggles to fill surplus capacity.