Fares on that line are priced by the lead operator, CrossCountry.
Their Off-Peak Returns carry a "2V" restriction - OUT and RTN portions valid after 0930 weekdays. The company is also known for its very high walk-up fares (both Off-Peak and Anytime).
Since all trains from Birmingham to Alnmouth will call at major stations like Derby, Sheffield, York, and Newcastle; your best bet is to look at "splitting" at these stations, into a series of Off-Peak Returns. Note that these shorter tickets
may not be priced by CrossCountry, meaning an Off-Peak Return
could be valid on any train, even before 0930.
For example, if taking the direct 0759 train:
07:59 Alnmouth [ALM]
Birmingham New Street [BHM]
11:27 3h 28m
Calling points Arrives Departs
Morpeth [MPT] 08:12 08:13
Newcastle [NCL] 08:30 08:35
Durham [DHM] 08:46 08:48
Darlington [DAR] 09:03 09:05
York [YRK] 09:32 09:35
Doncaster [DON] 09:57 09:58
Sheffield [SHF] 10:20 10:23
Derby [DBY] 10:50 10:53
This train would require the £141.90 Anytime Return with railcard!
However, buying the £39.25
Alnmouth-York Off-Peak Return which is valid after 0400, a York-Sheffield Anytime Return (£15.20), a Sheffield-Derby Off-Peak Return (£12.95) and a Derby-Birmingham Off-Peak Return (£10.70) pretty much halves the cost. You just need to obey the restrictions on the return leg - these can be easily found on
www.brfares.com
Other splitting points may be cheaper - have a play around. Also remember that if your final destination is not Birmingham New Street but somewhere like Selly Oak or another local station, tickets to here from another city are likely to be the same price as ones just to Birmingham Stations and so you wouldn't need to buy a further connecting ticket.
I recently completed a journey from Yorkshire to Devon on a single CrossCountry train, booked less than a week in advance. By splitting Advance Singles I was able to almost halve the cost, including a couple of the back-to-back legs being in First Class where these tickets were cheaper.