Anyone who grew up in a city during the Forties and Fifties learnt two things about the Salvation Army. Its officers braved the saloon bars of public houses, selling the War Cry and demonstrating that not all total abstainers are po-faced bores. And it helped the very poor by distributing tea and sandwiches. I knew very little more about the “Sally Ann” when I began to write a biography of its founder, William Booth.

Booth had all the strengths, and many of the weaknesses, necessary in a man who founds a religious movement which, in his own lifetime, acquired a worldwide membership. One of the weaknesses was the habit of claiming credit that others deserved. His “cab horse principle” was plagiarised from Thomas Carlyle. When a London cab horse fell, passers-by helped it up and sent it on its way without first demanding to know if the animal’s stumble had been its own responsibility. Surely, Booth argued, we should behave towards men with the same compassion we showed to horses. That principle — help where help is needed, without blame or recrimination — is the basis of the Salvation Army’s social work.

Halfway through writing the biography, I felt compelled to see how the modern Salvation Army helps the “men living under bridges” whose belated discovery had so distressed Booth before he published In Darkest England. So, one Saturday night, I joined the patrol covering the Strand and the Embankment, downstream from Parliament Square.

The battered minibus in which we travelled was driven by an out-of-uniform officer. But his platoon of helpers were, to my surprise, middle-aged ladies who would not have looked at their best wearing sweaters emblazoned with the motto “Blood and Fire”. They were women who wanted to do good. But they were not “do-gooders”. I have never met less self-righteous people — or a group that was more devoted to the task of providing succour and comfort.

Having represented an inner-city constituency for more than 30 years, I imagined that there were few sorts of human degradation which I had not witnessed. I was wrong. The men and women huddled under dirty blankets in the archways behind Embankment Gardens were more wretched than anything I had ever seen. Most of them were either mentally or physically ill. There was little evidence of drink (the curse of Booth’s day) but much of drugs. I assumed — perhaps because it was what I wanted — that we would pass out tea and sandwiches and swiftly move on. Instead the ladies started conversations.

At first, they talked about everything and anything — the weather, the traffic, the stars. Then, gradually, they got round to the subjects that were the real objects of the conversation. “Wouldn’t it be sensible to see a doctor? It could be done without any embarrassing questions being asked . . . What about a clean shirt or warm jumper?” No one was asked to pray or give thanks to the Lord. In the small hours of the morning, after the last call had been made and the night’s work was done, we drove to a cul-de-sac near Gray’s Inn and, after eating what was left of the sandwiches, said a prayer of thanks for being allowed to be of service. Although they made clear that atheists were not expected to feign religion, I joined in.

About a year ago, I made my second sortie with the Salvation Army’s care and comfort battalion. In Leicester a young man in the doorway of the ironically derelict Citizens’ Advice Bureau had to be roused from a deep sleep. Would he not, on such a cold night, prefer a place in a hostel?

The minibus was available to take him there at once. The offer was declined for the not-altogether-rational reason that the hostel was “no more than bed and breakfast”. Then there was a moment of anxiety. “You will be round in the morning, won’t you?” He was assured that breakfast would, as always, be served in the shop doorway. Would he like a new sleeping bag then? The young man took offence at the suggestion. For he retained a perverse pride in the few worldly goods he still possessed.

“I have”, he said, “one which is state of the art. It was given me by the Salvation Army.”

Anyone who thinks that such young men are treated with too much indulgence ought to pause and consider the conversation in the minibus as we moved away. “I’ll get him off drugs if it’s the last thing I do.”

The next stop was a municipal park notorious for muggings and rape. The baseball cap and sweater that bore the insignia of the Salvation Army were, I was assured, a guarantee of safety. Everyone knew that the Salvation Army existed to help, not to pass judgment. So it does. But it also works to rehabilitate. Its strength is the way it encourages a return to the paths of righteousness without seeming righteous itself. Officers of the Army regard exhibitions of moral superiority as a sin. They believe in a strict, indeed a rigid, code of personal discipline and religious belief. But they do not impose their beliefs on those they aim to help.

They share Booth’s conviction that deprivation is the Devil’s ally and that a man or woman, raised from the gutter, is more likely to find God than one who is left to rot in squalor.

It is not necessary to share the Salvation Army’s theology in order to admire its work. I list the volunteers who work the streets at night among the best people I have ever met. I wish that I had the courage and grace regularly to join them. In my inadequacy, I do no more than assert that they are worthy of your support.

The Salvation Army is a beneficiary of The Times Christmas Charity Appeal.

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