Hi I had email from BCNorwich which he qouted below which did not help at all. But it help a little
The old M&GN and Great Eastren routes should have been top of the list as it effects most of the roads and byways etc when users edit it as well using josm.
(Hello There and welcome to OSM,
I'm sorry to have to inform you that you have placed on the map a railway that no longer exists and in a manner as if it does exist. If you look at other old sites of railways nearby (Marriots Way for example,) you'll see them tagged as railway=abandoned. Please see this link for further information :- http://wiki.openstreetmap.org/wiki/Talk:Railways#Abandoned_railways_where_all_evidence_has_been_removed
In my opinion something that cannot be seen on the ground, as is the case with a lot of the old railways, ought not to be mapped. However to be completely open this thread advises otherwise, https://help.openstreetmap.org/questions/650/does-osm-use-any-historic-data-or-want-to
It might be better to tag the sections that are now absolutely non-existent (some are ploughed up and reverted back to farm land), as railway=dismantled.
Has I can say for better e.g. it should be railway=M&GN and railway=GE would been better for trainz users and railway families or railway people that know the railway better