... The veteran campaigner for the poor and the NHS had plenty to say about the brutal Great Depression, the horror of postwar Hamburg – and the advice he gave Ed Miliband

You’re a 91-year-old, but you speak like a youthful rebel.

It’s because I never admitted, ever, that I was getting old. I “retired” at 65 but I didn’t really retire. When I reached 75 I backpacked across Europe. I would take off, going to Belgium to look at places that I’d visited during the second world war. I went back home; I got restless again. So I took a plane to San Francisco and travelled all the way through southern California. My youngest son’s wife said: “You’re crazy!” I said I’d rather be crazy than sitting waiting for death. I really enjoyed my life. The saddest part was when my wife died in 1999 – that’s when my wanderlust started. My house didn’t have any thoughts for me.

What was it like growing up in Barnsley in interwar Britain?

I don’t know how you can sum it up because it was so brutal – there was no other word for it. I was born five years after the end of the first world war. That alone was a disaster that crippled soldiers. That’s the trouble with wars, too: after a war, the government doesn’t give a damn about the soldiers. There were guys with no arms or legs who were living under the same desperate circumstances as everyone else.

My elder sister died in the poorhouse at the age of six from tuberculosis. For a young kid, I think the worst part about it was – I just couldn’t keep up with my studies. For one thing, we couldn’t stay in the same place – I must have gone to at least six or seven schools by the time we’d finished hopping around because we couldn’t pay the rent here or something else. And then this job I had which took from after school until just about dark and on Saturdays. So I was just buggered by the time it came to weekends.

Do you remember your youth as a time of hunger?

Oh yes, absolutely. If you didn’t have a job, you didn’t have money; if you didn’t have money, you didn’t have food – that’s the whole point. That’s why I did this barrowboy job as a child. I got four shillings a week and managed to put a little bit more food into the house. I had a maths teacher – Froggie Dawson – he was a rather fattish man, with a corpulent body. I remember one time I hadn’t gone to school for a couple of days; it was in the winter, and the snow was on the ground, and so when I came back, at the end of the class, he made me stay behind, and demanded to know: “How come you were off school yesterday and the day before?” And I remember lifting up my shoe – and I had cardboard there for a base, and it was all soggy. So he said – go home now, get there as quick as you can, and see me after school tomorrow. So after school the next day, when all the others had gone, he reaches into his drawer for a pair of shoes. And they were a bit big but I knew I could stick some newspaper in the front, and I thanked him profusely [sobs]. We didn’t have any hope at all that I could remember, until after 1945. We just didn’t believe they were going to do anything about it, because we existed under such a cruel system for so long.

Facebook Twitter Pinterest ‘We didn’t have any hope at all that I could remember, until after 1945’ ... Harry Leslie Smith. Photograph: Graeme Robertson for the Guardian

Your family life was difficult, wasn’t it?

My mother and this man she’d taken up with got to drinking extensively and my sister and I were left pretty much in charge of the man’s youngest son. He was only a baby. So we had to take care of him when they were down the pub. We stayed awake when they came back – and then the fight would begin. Thumping and banging, dishes flying. We would get up in the morning: cups, saucers, plates left over the floor like a ship had collapsed. Another time, we had to throw ourselves on the man’s back because he was beating our mother. It was a sad time.

You’re a Yorkshireman. I was born in Sheffield ...

I got pissed aged seven in Sheffield! My Uncle Harold said to me one day: “How would you like to come to Sheffield? It’d be a day out for you, something different. And I said, “Sure, why not!” So he took me into Sheffield – he had to go around the betting places to place bets and afterwards he said, “We’ll just go into this bar and we’ll have a drink, then we’ll go home.” So he went in, ordered a drink, and then the barman looked at me and said, “What’s the young chap going to have?” Uncle Harry said, “Give him a gin and orange.” By the time I finished it, he had to carry me to the bus stop. My grandmother gave him hell when we got back because I was still dozy.

You joined the RAF when the second world war broke out.

Yes, and became a wireless operator. It was a six-month course. I learned about morse code, learned to send and receive, about 22 words a minute, and I also learned about receivers and transmitters. It changed my life. For the first time I knew I’d have three meals a day and get a paypacket at the end of the week.

You were sent to Germany after the fall of Adolf Hitler in 1945. What do you remember?

It was terrible in Hamburg. The smell of death was just unbelievable, and there were 50,000 people still under the ruins. It was like a giant mountain. Can you imagine? I saw lots of bombed buildings in Belgium and Holland, but not to the extent that it was in Germany. It was senseless. I entered Germany with a feeling of enmity, disgust at what they’d done during the war, but I soon realised they were no different to any other nation. They still had their worries about their children. They were starving.

Harry Leslie Smith (left) with RAF mate, Jack Williams

That’s where you met your wife, isn’t it?

Once we got drunk in Hamburg, and commandeered horses through the city. My wife saw me riding drunk on a horse and thought, “What a bunch of idiots.” When I first saw her, I thought, “She’s really beautiful.” I offered to carry her bag, the usual, and she said: “You’re not Canadian, are you?” When I said no, she said, “That’s all right, Canadians don’t have a very good reputation.” At that time you couldn’t go out in public with a German woman and it was against the law to cohabitate, so I had to walk 50 paces behind.

She wasn’t very impressed when you brought her back to Britain, was she?

The conditions for the German people and Dutch people was so far advanced from what we had in England. They all had inside toilets, they had baths with hot running water, electric stoves. I couldn’t get over it, because we were still washing with a tin bath in the kitchen. So when my wife came back to England she was pretty appalled. When I told her, “You’ll have to use a potty here, dear”, she said, “There’s no way I’m going to use a potty, doesn’t matter what time of day or night.” So in the middle of the night, she’d say, “I’ve got to go” and we got up, found some warm clothes and went to the front door. The toilet was about 10 houses past. I had to stand there while she used the toilet, and go back to bed again. I said, “I hope you don’t have to go again tonight!”

You’ve told David Cameron to keep his “mitts” off the NHS. What would happen if the NHS was dismantled?

Then you’d be back to my early childhood when the rich could buy care and the rest of them had nothing. They either lived or died according to their genes or their strength or will or something. It’s not fair. I think everyone has the right to his life and to live it to the best of his ability. To even think we could live without an NHS is just unbelievable to me, and I think it’s about time governments really worked to fund it properly, even at the expense of getting some of these rich people paying more taxes.

Facebook Twitter Pinterest Owen: ‘What advice would you give my generation?’ Harry: ‘They have to get up off their arses and vote’ ... Photograph: Sam Frost for the Guardian

What’s your fear about the situation facing people in Britain today?

Even now I shudder to think what people are going through to feed their children. It’s so bloody unnecessary as far as I can see. It’s appalling. It’s all these zero hour contracts – how could the government allow something like that to even come into existence? You can’t take money from the average worker and not from the big businesses. The government hand everything out now to private companies – in the old days, the government used to be the ones who looked after everything. How the hell can you privatise water? It’s the basis of life.

What advice would you give to Ed Miliband?

I spoke with him at this year’s Labour conference and actually I told him – I said, you have a chance now to be a prime minister who will go down in history! But you have to assert yourself and you have to make it clear who you are and what you’re planning to do! But it didn’t seem to work. He said, “Yes, yes,” and patted my arm. And it’s true – anyone who came up now with a good plan to rule Britain could rule it for the next 20 years, because it’s at the stage where it can be saved and it could be saved.

What message would you give to my generation?

First of all, I would suggest that voting should be made compulsory, and until it is, what they have to do is get up off their arses and go to cast their vote. If they don’t like any of the people who are on the ballot, spoil the ballot! Spoiled ballots are counted too, they might not realise it – and if the government comes to power and finds only 37% of the people are voting for them and the rest are saying, “Shit on you!” maybe there’ll be some changes.

• Harry’s Last Stand by Harry Leslie Smith is published by Icon Books at £8.99. To order a copy for £7.64, visit theguardian.com/bookshop or call 0330 333 6846.