I am looking at off-peak return tickets between Cambridge and Saxmundham which normally require a change at Ipswich. However, for the return journeys it's actually 18 minutes quicker to go Saxmundham-Ipswich-Ely-Cambridge rather than Saxmundham-Ipswich-Ely (all travel is on GA). National Rail website says they can't price the journey if I go via Ely, and Greater Anglia website doesn't even list it. Is the route valid or not?