Hi
You are absolutely correct, the best thing you can do to help a rough sleeper is to contact Streetlink, the person then gets logged and action has to be taken to help them. I believe Thamesreach runs the outreach service for Lewisham currently, and there is also a Lewisham number
Lewisham: 020 8778 0877.

It might seem harsh, but you should not give support that will help sustain someone's rough sleeping, or money that might be spent on feeding an addiction, you will be compounding their problems and make it more difficult for them in the long run, ‘cruel to be kind’ as they say. As you have done before, if you wish to give them something, make it a gift of food or a warm drink, but more importantly if you can find time to speak to them, hear their story, and point them towards help to get off the streets.

Homelessness and rough sleeping has increased by 16 per cent in the last year. Many rough sleepers have no recourse to public funds. You might find this article of interest: http://www.bbc.co.uk/news/uk-england-38719087