Image copyright PA

Spending time with nature offers "precious breathing space" from modern life, Sir David Attenborough has said, as he called on the public to join the world's biggest butterfly count.

The naturalist said watching butterflies in his garden takes his mind off "the woes of Brexit".

The exercise involves spending 15 minutes counting butterflies and submitting the sightings online.

The majority of butterfly species have been in decline for the past 40 years.

However, this year, weather in the UK - a cold winter followed by settled weather during a late spring and summer - have created the right conditions for butterflies to flourish.

Species expected to do particularly well include the holly blue and red admiral.

Image caption This year could be a good one for the red admiral butterfly

But if the hot conditions create a drought, the results could be "catastrophic" as plants wither and insects die through lack of food, said the charity Butterfly Conservation, which organises the count.

This happened in 1976 when the butterfly population collapsed after the hot summer.

As part of the Big Butterfly Count, Butterfly Conservation is asking the public to spot and record 17 species of butterfly for the next three weeks.

In addition to contributing to conservation knowledge, mental health charity Mind says spending time in nature can help alleviate problems such as depression and anxiety.

Image copyright PA Image caption The Big Butterfly Count takes place between 20 July and 12 August

Sir David said being in nature "offers us all precious breathing space away from the stresses and strains of modern life".

"Some of my most memorable experiences have happened when I've been simply sitting and watching the wildlife that lives where I do," he added.

And he told BBC Radio 4's Today programme: "I'm asking people turn their mind away from squabbles and problems about what's facing us with Brexit, sit in a quiet place where the sun is shining and see how many butterflies come.

Image copyright PA Image caption Butterfly Conservation President Sir David with a south east Asian Great Mormon Butterfly on his nose in 2012

"That simple pleasures of looking at butterflies in the garden is calming to the soul and spirit and good for us all."

Asked on BBC Breakfast whether he had discussed the issue of plastics with the Queen when he met her, Sir David said he had not - and declined to be drawn on the royal family's attitude to the environment.

Last year's big butterfly count was the largest ever with a record number of people - over 60,000 - submitting sightings.

But despite this, the average number of butterflies seen per 15 minute count was the lowest recorded since the survey started in 2010.

The reduced numbers of butterflies was partly due to "topsy-turvy" weather last summer, which was one of the wettest summers for 100 years.

Are butterflies in the UK under threat?

According to Butterfly Conservation, three-quarters of British butterflies are in decline.

Five species of butterfly have become extinct in the past 150 years.

The charity says that habitats being destroyed or deteriorating are the prime causes of long-term decline.