If someone wants to volunteera portion of their time while on a holiday in London, would you suggest contacting churches, soup kitchens, etc. It's been over 10 years since I was a student there, so I don't know the resources to consider.
Thanks.

Try a google.co.uk search for Charities, Volunteer orgs, etc. There are more than enough to find something you would like to volunteer with. I think there are some orgs like in the U.S. that collect food from restaurants for soup kitchens.

I applaud your intentions, Pilgrim.

There were at least two threads on this topic on Fodors within the last year or two, and one of them had a lot of helpful leads. You might try searching for likely terms. I don't have time now (at work), but if you have trouble finding them, post here later with what you tried searching for and maybe I can find them.

Churches, being less significant in the UK in every way than in the US, may not necessarily be the best place to start.

Try the www.csv.org.uk site, though this might be a tad bureaucratic for you. One London page is http://time/GO/GO+London.htm

If you've a particular thing about soup kitcheny activities, go to www.crisis.org.uk

While I applaud your public-spiritedness, I don't think it's simply a matter of getting in touch with an appropriate charity. Because of stringent legal, child protection and health & safety issues, every volunteer has to be vetted with a police check and references obtained. If you can find a voluntary body willing to take on all-comers, it isn't a sign of their generosity but rather foolishness. I think the best way a visitor can help the disadvantaged is to make a generous donation to Shelter, Crisis, Salvation Army etc.

Thank you for your views. London was such a wonderful part of my formative years. I just wanted to give something back. When I go back annually, I get to see friends and museums, but my heart still aches for those hurting.I thought time in addition to financial gifts might be good, but I never thought about the security concerns. You offer several good options. Thanks for your time.