Network Rail owns all the stations and from their website....
http://www.networkrail.co.uk/aspx/777.aspxPart of which states....
When you arrive at a station, please let the staff at the Network Rail Reception Desk know that you are on the station. This will help keep station staff informed so that they can go about their duties without concern as to your reasons for being there.
You may require a platform ticket to allow access to platforms.
The above seems to suggest that these rules only apply to the 15 or so stations that Network Rail directly manage -
BNS▸ ; Leeds; Manchester Pic; The big ones in London; etc. There is perhaps some lack of clarity over the hundreds of other stations, such as Maccesfield.
Also stated on the same webpage by Network Rail is...
you may very occasionally be asked by station staff to move to another part of the station or to leave the station altogether. Station staff should be happy to explain why this is necessary. If you are travelling by train, they may ask you to remain in the normal waiting areas with other passengers. If this occurs, please follow their instructions with goodwill as staff have many things to consider, including the safety & security of all passengers, and are authorised to use judgement in this regard.
Anything else quoted by newspapers is just designed to create a story and sell "copy".