GBT has recently caught my attention. Only wish I has seen it...

GBT has recently caught my attention. Only wish I has seen it earlier as it has had a strong run up in price, but I am never afraid to join a good story even if it is already recognised. GBT looks like a good business, rapidly expanding without the need to issue any new shares. A nice profit lift in recent years. Good R&D to maintain leading edge.
Lots more yes, but I have a question...
It looks to me that their forward growth path is reliant on successful expansion into the UK and the US.
Am I right to think that they currently have only one large client in the UK and none yet in the US?
It seems to me that this must be a competitive industry so GBT must be facing a true test of how good its technology is against overseas competitors.
I would appreciate any comments on this.
I plan to ring the company in the near future to have a chat, so any decent questions on key issues appreciated.

Cheers
Gosouth.