Grateley- Waterloo. Why change at BSK?

[Diplodicus]

I’m trying to purchase an advance ticket GRT - WAT and it the journey says I have to change at BSK even though I’m already on a WAT direct?
Is this correct and why?

 

[Kite159]

Most weekday services from Grateley are only running to Basingstoke at the moment (reduced timetable), requiring a change at Basingstoke to the ex-Weymouth.

After the 08:27 service the only ones which carry on to London are the 14:59 & 15:59.

 

[JonathanH]

I’m trying to purchase an advance ticket GRT - WAT and it the journey says I have to change at BSK even though I’m already on a WAT direct?
Is this correct and why?

When is the journey being booked for? Does the service from Grateley definitely go to London Waterloo?

 

[Diplodicus]

When is the journey being booked for? Does the service from Grateley definitely go to London Waterloo?

No, sorry. I’ve just downloaded the timetable. My mistake.