fwiw ParsingFright you wont lose your railcard on PIP if you meet the 50m criteria for high rate mobility DLA
the 50m is used to get "standard rate" mobility (equivalent to low mobility on DLA) under PIP and the 20m is a criterion for the "enhanced rate" and is the high mobility equivalent
unlike DLA you can also "mix and match" criteria for points eg if you meet the 50m criteria for physical reasons AND need someone with you or can't always follow/ask for directions for MH/LD reasons you can get high rate mobility, it is stricter than DLA physical-wise, ridiculously so, but opens up the high rate for people with severe agoraphobia/anxiety/non-disruptive & non-aggressive LDs who don't have 24hr care needs, also for people with a combination of physical and non-physical disabilities.
it is important to mention though that if it hurts you to walk, there is your 20m and your enhanced mobility under PIP. if you can't safely, reliably, repeatedly walk 20m in a reasonable time frame, you can start arguing your case from there. but why should you have to. The claimants own doctors reports should come first imo and Atos should only get involved where claimants REQUEST an external assessment due to unsupportive GPs etc. (raging lefty/semi activist here, sorry)
also if you need someone with you in case of falls/fits you can get high rate mobility under PIP whereas under DLA that need for accompaniment would only get you low rate mobility. this is not solely a MH criterion as some people think it is, but about whether it is safe for you to go out alone - eg if you might have an absence seizure while crossing the road, or your hip might dislocate while walking, or you have poor vision but are not fully blind and could miss seeing a car coming where someone with normal vision might see it.
you can get a disabled person's railcard with any rate of DLA mobility
the same goes for PIP: from the railcard website -
People now receiving Personal Independence Payments at any level for either the Mobility or Daily Living components, are eligible for a Disabled Persons Railcard.
Same as DLA - people on middle/high care or any rate mobility could all get the railcard and PIP is supposedly an equivalent
cold comfort really when you take into account the sop of 2k that Motability are throwing at people who are losing cars/scooters/wheelchairs and much of the money to pay for them within a couple of years all because of 30m.