For a GTG overflow customer (i.e. direct GTG), if they are going on a land based holiday but need higher cancellation than £5,000 per person (Platinum), you can offer them the Cruise based GTG policy (Cruise Specific or Cruise Specific Plus), which can cover a customer with up to £10,000 Cancellation Cover per person. If you increase the cancellation cover, Silver, Gold and Platinum will become unavailable, as this needs to be on the cruise policy only.
However, it is optional for GTG customers only, if they do want extra cancellation. That is why GTG offer the Silver policy, that only comes with medical cover.