A homeless man who was handed a sandwich by a schoolgirl despite a Starbucks barista cruelly telling her to 'let nature take its course' has praised the 14-year-old for her 'overwhelming' generosity - and slammed the coffee chain.

Liam Anderson, 20, from the Pollok area of Glasgow, said he felt 'very thankful' to Amy McIlroy for the food but 'shocked' by the attitude of the staff member at the cafe in Exchange Place.

He told MailOnline: 'When the girl bought me a Starbucks, it was quite overwhelming, to be honest. I thought, 'Wow, people do care!'

Liam Anderson, 20,(left, pictured today) from the Pollok area of Glasgow, said he felt 'very thankful' to Amy McIlroy(right, undated photo) for the food but 'shocked' by the attitude of the staff member at the cafe in Exchange Place

Undaunted, Amy went ahead and bought the sandwich to give to the boy, and complained to the coffee giant on Twitter

Amy wrote after the incident: 'So f****** disgusted. @StarbucksUK went in to one of your Glasgow branches to get some food for a homeless boy who was physically shaking from the cold and was told off a worker that I'd be better 'saving my money and letting nature take its course'. I'm at a loss for words.'

Mr Anderson wanted to go into Starbucks but he was not allowed in. 'I was quite dirty and other customers get to go in no matter their circumstances,' he said.

'I was very shocked. It's unfair that I've been discriminated by the way I look. It's bang out.'

Mr Anderson explained that he became homeless after being neglected by his mother and falling out with his sister after going through the care system.

'I became homeless because my mum neglected me since I was about 14,' he said. Me and my sister went through care... I tried to leave care and now I'm waiting until social work gets me a house.

Speaking today, Amy said: 'I was really taken aback when the barista said that because I've never experienced that type of hatred or ignorance towards a stranger who hasn't done anything to merit such vile behaviour.'

Liam Anderson, 20, from the Pollok area of Glasgow, said he felt 'very thankful' to Amy McIlroy for the food

Mr Anderson (pictured) said he was 'shocked' by the attitude of the staff member at the cafe in Exchange Place

Mr Anderson had been staying at a homeless night shelter but says he regularly finds it is fully booked.

'At times I go grab a sleeping bag somewhere, get under an air vent then go to sleep,' he said.

'It is quite scary at times but once you get to know a few faces it's not too bad. People talking to me gives me comfort because they ask if I'm okay and that.

'My wee sister has her own house now but we fell out in care. They had to separate us because we weren't talking to each other. I've lost contact with her through Facebook and the whole lot. She's blocked me and everything.'

Speaking today, Amy (pic in an undated Facebook photo) said: 'I was really taken aback when the barista said that because I've never experienced that type of hatred or ignorance towards a stranger'

Mr Anderson eventually hopes to get back on his feet, get a flat and go to college.

He said: 'I now would love to be like a football manager and go to college. Not professional but over 35's or something.'

Amy added: 'My friend was with me at the time and she was saying that the barista was not worth responding to but I told him that it was a disgusting thing to say and that I hoped he didn't speak for Glasgow.

'There are a million circumstances that could lead to someone becoming homeless. Starbucks should be held accountable for clearly not training their staff well enough in customer service.'

Starbucks are now on the receiving end of a customer backlash.

Marianne Gallagher tweeted: 'I bought a young boy (likely the same one) a coffee from that Starbucks on Friday. I'll take my money elsewhere in future.'

Bethany Scott added: 'Wow. Bye Starbucks. I'll spend my money at Pret instead.'

Another Twitter user added: 'What kind of heartless b****** could say this about any human? Hear so many horror stories about Starbucks, you wonder what their teaching/training process is.'

Amy's mother, Liz, has praised her daughter for her handling of the situation and thoughtfulness.

The callous comment was made by a customer at the Starbucks store in Exchange Place, Glasgow

Undaunted, Amy went ahead and bought the sandwich to give to the boy, and complained to the coffee giant on Twitter. She is pictured in an undated social media image

Dozens of people hit out at the barista's behaviour with one Twitter user vowing to take their money elsewhere

Mrs McIlroy, 52, said: 'She's very soft-hearted and has never had that boy out of her head since.

'I'm proud of her. She's that sort of person who is always thinking of others.'

There has been mounting concern for the plight of the homeless during the spells of extreme cold weather this month.

A homeless veteran died in Edinburgh a week before Christmas while sleeping rough.

Darren Greenfield, 47, who sat at the top of the Waverley Steps on Princes Street, died after he was admitted to hospital.

A spokeswoman for Starbucks UK said today: 'We're urgently investigating what has happened here and have been in touch with the customer directly to apologise.

'We believe in creating a place that is welcoming for all and we are disappointed that this incident does not represent the values we expect in our stores.'

Starbucks have regularly been the subject of tax avoidance allegations and in 2015 were ordered to pay back Euro 30m in Holland.

Last year it was reported that their UK profits had dropped by 60%, although they still turned over £13.4m. They blamed the drop on Brexit and a slowing economy.

Mr Anderson told MailOnline: 'When the girl bought me a Starbucks, it was quite overwhelming, to be honest. I thought, 'Wow, people do care!'