Only 50% of UK adults would feel comfortable approaching someone they were concerned about in public, according to new research by Samaritans.

Fears their approach wouldn't be welcomed, that they might make things worse or just wouldn't know what to say, were all cited as reasons for holding back.

Yet, some simple small talk could make a massive difference to somebody struggling with dark thoughts, and potentially even help save their life.

"I had some very dark days, thinking I was useless, but I got through it by talking to people," says presenter and mental health advocate Gail Porter, who is supporting the latest phase of Samaritans' Small Talk Saves Lives campaign. "Be nice, listen to each other, talk to each other."

The campaign is in partnership with Network Rail and British Transport Police. Shona Gibbs, Samaritans' acting head of rail, says their research included asking people who've experienced suicidal thoughts about what they found helpful when approached by concerned strangers.

Verbal interventions - including small talk and active listening - were found to be the most helpful things a person can do to help.

"What's most important is acting on your gut," says Gibbs. "If something feels off, trust yourself in that moment and check in on the person you're concerned for."

Porter agrees, saying: "People worry too much about what people might think. You shouldn't worry, you should just think: that person doesn't look happy, I'm just going to say something really quickly - if they don't want to talk to me, it's ok, but at least I've tried."

The Scottish TV personality and former model, who presented shows including The Big Breakfast, Top Of The Pops and TFI Friday in the Nineties and early-Noughties, has always been honest about her own dark times - which included suddenly losing her hair to alopecia in 2005, facing divorce, bankruptcy and homelessness after her work started drying up, as well as the death of her mum in 2009. At one point, Porter was sectioned under the Mental Health Act.

"I'd lost my hair, I'd lost my mum, I'd lost my home, I was bankrupt, I was homeless, and I just thought, 'Oh my gosh, this can't get any worse, can it?'," recalls Porter, 51.

"People can have very dark thoughts, and that's why we need to talk to each other."

Thankfully, she is now feeling great and much stronger - but is determined to use her own experiences to help others going through their own dark times.

Porter turned to the Samaritans at her lowest point, and found chatting to the charity's volunteers was a "great release", which helped her turn a corner.

"I'm working with The Samaritans because they've seen me go through highs, really bad lows, and back up again," she explains.

"I've been very open about it, I'm not embarrassed, I'm not ashamed. This is what's happened, it's been a bit rubbish and a bit sad, but I'm still standing and I'm still smiling. And if I can do it, anyone can.

"People can have very dark thoughts, and that's why we need to talk to each other. A lot of people get anxious about whether to say something, but it's really quick - you just go up and say: 'Is everything alright?' And if they say yes, then fine," she adds, emphasising the campaign message.

"I do it all the time," says Porter. "I live in London and a lot of people say, 'I'm fine', or just ignore you and walk away, but a lot say they're alright, or just thanks for saying something."

She's been on the receiving end of such kindness herself too, and was incredibly grateful for it. "I was a little bit tearful one day on the underground," Porter recalls, "and someone came up to me and gave me a little packet of tissues. He just put it in my hand. He didn't say anything, he just tapped my hand and sat back down.

"It meant such a lot to me. I didn't want to make anyone feel anxious because I was sad, but someone did a tiny thing and it made me feel better.

"Even just a smile on the Tube if someone looks sad can help. I've seen people on there who've been on the phone and it looks like they're arguing and crying, and I'll just smile and give them a nod, and I'll get a smile and a nod back, and sometimes that's all people need.

"It's great to talk, but if you don't feel like somebody wants to talk, just smile. Acknowledge each other. We're all in this together, we're all going to have bad days and good days, but it's nice to know people are smiling or listening and asking if you're ok."

Porter, whose daughter Honey is now 20, says she's now in a good place.

"I'm great now, I'm really good - my daughter's doing great, I'm doing lots of really nice talks around the country, and I'm doing a little stand-up show at the Edinburgh Festival. I talk to people so much now, because when I went through my bad times, I didn't pick up the phone to my friends because I didn't want to burden them.

"This is why this campaign is so important to me. I just went for so long not telling anyone what was going on, and it was just getting, in my mind, worse and worse and worse, because I wasn't asking for help. I wasn't asking for someone to give me a hug or just listen to me for a bit."

Gail Porter is helping the Samaritans remind people we all have the potential to be lifesavers by simply striking up a conversation, as part of Samaritans' Small Talk Saves Lives campaign (samaritans.org).