Public Liability Insurance

Hi

was wondering do railway photographers need Public Liability Insurance? I have been doing free photography for charity events for years, marathons, charity balls, walks, pub quizzes etc and to be honest I regard myself as no more than another member of the public with a camera or a participant in the event taking snaps. There are a couple of events I have done in the past that take up a full day and evening, so I ask for money to cover my expenses. For the next event I have been asked to produce a Public Liability Certificate. I have found some camera equipment insurance companies, Glover & Howe, Aaduki, Photoguard, but their quote is more than I usually make from charity events in a year?

So my question is do I have to take out Public Liability Insurance even though I am not making any real profit?

This brings me to my second question. I get the photos published from time to time in magazines, should I have Public Liability Insurance to cover me standing in a field or on a street taking photos? I would consider it more for professionals who make a living from photography in case some member of the public trips over their equipment? I try not to take photos from station platforms as they are private property (and not suppost to get anything published unless permission sought... don't think anyone follows that one including myself). I have seen many cases of people stepping and tripping over themselves at platforms and pedestrian overbridges in which members of the public are passing by. Do any of them have public liability insurance if someone trips over their equipment?

Any thoughts...