Marion Montgomery was signed off work sick when she started what she thought would be a local group to combat plastic litter strewn across beaches and paths in Aberdeenshire.

A year on, the Paws on Plastic Facebook group has mushroomed to 13,000 people from across the globe committed to collecting rubbish while on their daily dog walks.

Ms Montgomery, a primary school teacher from Stonehaven, had to take a year off work after contracting shingles.

During her recovery last November, her doctor encouraged her to continue walking her three-year-old Labrador, Paddy.

Ms Montgomery said: "I'm just not somebody that likes to sit still. Going from talking to kids in school and being really active to then just being stuck at home with no energy was just dismal."

As the "eco-person" at school, Ms Montgomery did a lot of research into the environment and found a scheme organised by the British Council on plastic pollution, signing up to take part.

She said: "It was encouraging young people to start a social action in their own area. There were lots of different people from different walks of life."

Although she fell ill during the programme and was unable to attend the group meetings, Ms Montgomery was able to continue with the project through online access.

She said: "I got the idea [for Paws on Plastic] because the only thing I was doing was going walks with my dog. I'd be fine for doing that for half an hour."

Now the owner of two Labradors, Paddy and six-month-old Ted, Ms Montgomery has always been conscious of plastic litter while out on their walks.

She said: "My dogs have always picked up litter. My old dog Murphy, he was really my inspiration, because he always picked up plastic bottles so I would go to the park and come back with a plastic bottle. So many dogs do that, it's in their nature."

Recognising that dog owners have been natural litter pickers for years, keen to clean up their local environment, the idea for a her social action group was born.

She said: "It's something I've always done and you can't really throw it back to the ground if your dog's been playing with it.

"I found we were walking past the same litter every day. You are scanning to make sure your dog isn't going to pick up anything that would hurt them and then you think there are other animals out there that could be harmed by that as well.

"It's fantastic doing beach cleans but the tide comes back in and more litter is washed ashore, whereas dog owners are out every day, a few times a day. If you just, as part of their everyday routine, pop a few bits in your poo bags and take it home for recycling, it makes a huge difference."

Initially adding some 120 dog walking friends to the newly formed Facebook group, Ms Montgomery watched as it grew rapidly with friends of friends adding everyone they knew with a dog.

She has already noticed the impact the group has had locally in Stonehaven that now boasts 250 Paws on Plastic members - and barely any litter left on the ground where there once was. Now with a presence on Twitter and Instagram, the group keeps growing with over 1000 members added in the first week of the new year.

With members from more than 60 countries including Australia, Canada and Norway, the social impact of the group has been far-reaching.

Ms Montgomery said: "The impact of disposable culture has been huge everywhere."

Purposely encouraging people to pick up only two pieces of litter on every walk so to not overwhelm anyone, Ms Montgomery finds that it's "almost impossible to not pick up more" and the group photos include many with bulging carrier bags of waste collected on walks.

She said: "It's so addictive. If you can get people to pick up a couple of bits they start to notice it and just can't walk past it.

"I worked out that if you pick up two pieces on two walks a day members are very close to picking up 20 million pieces a year. That's around 1500 pieces a year each person would have picked up so it has a huge effect.

"I would like it to just be a normal part of dog walking, or all walking. The more people see it, the more it becomes normalised and there comes a point where we all have to take responsibility."