There shouldn't be a problem as it's shown in the National Rail Journey Planner. Just to back up what has been said in the past:
This guide shows the full range of permitted routes available for use with tickets on
the National Rail network. The content has been approved by the Department for
Transport. If you are planning a journey we would strongly advise you to make use of
the Journey Planner at
www.nationalrail.co.uk.
Any ticket indicated for use in
conjunction with a particular journey when using the Journey Planner will
automatically be valid for the route and service indicated.Which forms part of the bolded part in the
NRCOC▸ :
13. The route you are entitled to take
(a)
You may travel between the stations shown on the ticket you hold in:
(i)
a train on which you are able to make your entire journey without changing
trains;
(ii)
trains which take the shortest route which can be used by scheduled
passenger services; or
(iii)
trains which take the routes shown in the National Routeing Guide.
I am interested how it has been implemented to allow it in the online systems. I potentially think this easement
may be the reason:
700007
Customers travelling between Chichester and Cosham may double back between
Hilsea and Fratton. This easement applies in both directions.