I will be traveling between Newcastle and Edinburgh in August using public transit. I see there are buses that I can use to reach Bamburgh, Holy Island and Dunstandburgh Castle, but the web sites indicate there is reduced service for buses running on Sunday. I'm not seeing exactly what the Sunday schedule is - can anyone point me to someplace that actually says what the schedule is for bus services along the Northumbria cost on Sundays in the summer?

It is too early -- it is very possible the schedules might change by next summer -- look in maybe April.

Bus info is available from the council’s website

http://www.northumberland.gov.uk/Hig...sport/Bus.aspx

You’ll need to drill down and find the relevant bus operators. Arriva service X18 runs up the coast from Newcastle to Warkworth,
Amble, Craster (for Dunstanburgh Castle), etc.

Border Buses currently run the service from Berwick to Holy Island

https://www.bordersbuses.co.uk/timetables

Nothing on a Sunday. But as janisj says check back to see if a revised summer timetable is published (quite likely not).

Always check the tides for Holy Island

http://orawww.northumberland.gov.uk/...holyisland.asp

Sundays, and often Saturday afternoons, are bad times to need public transport in a lot of places in Europe.