She's banged the drum for the Gurkhas, she's the ambassador for an initiative to combat climate change and waste - but most recently, actress and keen gardener Joanna Lumley has turned her attentions to the plight of the humble butterfly.

Backing this year's Big Butterfly Count, the world's biggest survey of butterflies organised by Butterfly Conservation and Marks & Spencer, Lumley explains: "I've been fascinated by butterflies ever since being brought up in the Far East where they were, like many things there, huge, bright and extraordinary.

"The great heartbreak is to see how few there are today. Looking out on my garden now, and walking up and down it as I do every day, I'm not seeing any.

"This huge, scientific survey is actually counting the effect of mankind upon the natural world."

The public is being asked to take 15 minutes to participate in the count, which runs from July 20 to August 11 (prime time for butterfly activity), to help identify trends in species that will aid us in planning how to protect butterflies from extinction, as well as understanding the effect of climate change on wildlife.

Butterflies react very quickly to change in their environment which makes them excellent biodiversity indicators. Butterfly declines are an early warning for other wildlife losses. Almost three-quarters of UK butterfly species have decreased in population during the last decade, while the number of UK's larger moths has crashed in the past 40 years, according to a recent reports by a group of leading conservation organisations.

"The predictions are that numbers will be down again this year," says Butterfly Conservation surveys manager Richard Fox.

"As butterflies had such a bad year last year because of the wet weather, it's likely that fewer offspring will emerge.

"The Small Tortoiseshell has had eight bad years in a row and has declined by 74% since 1976. The weather last year would have been a major contributing factor but there are other things going on. They need suitable habitats to thrive."

This year's cold spring should not have affected numbers because cold snaps tend to happen when butterflies are dormant, so the insects simply come out later, he explains.

Lumley's own London garden, with its wild area of meadow planting at the end, should be a haven for butterflies, but she has seen few this year.

"That's quite a good area for butterflies, but I've maybe seen three this year," she explains.

She's nailed a moth overwintering box, featuring a nectar column, onto her pear tree, but so far it remains empty.

"Like the bees, suddenly there's been something catastrophic happening. Something we are doing is wrong. I suspect we have to blame it on our methods of farming, but I think it's also down to our way of living in our urban environment, getting rid of gardens and putting down decking, paving stones and tarmac, treating our vehicles as more important than our creatures."

Lumley, who is also the M&S sustainability champion, has planted many butterfly-friendly species in her garden.

"I love nettles, as do butterflies. We've got a tiny cottage in Scotland, on a wild hillside, and we have a meadow garden there. It's important not to be too tidy in your garden, because butterflies love species that aren't necessarily the smartest flowers. In London, I have Michaelmas daisies, buddleia, lavender, honesty, dandelions. Butterflies like all of these."

She'll be doing two butterfly counts - one at her London garden, the other in her Scottish retreat - and hopes that she'll have more luck during the three-week count than she has so far.

The Butterfly Conservation offers the following tips to attract butterflies to your garden:

:: Choose sunny, sheltered spots when planting nectar plants, because butterflies like warmth.

:: Select different plants to attract a wider variety of species.

:: Prolong flowering by deadheading regularly, mulching with organic compost and watering well.

:: Don't use insecticides and pesticides which kill butterflies and many pollinating insects.

:: Grow plants which will attract butterflies including buddleia, Verbena bonariensis, lavender, perennial wallflower, marjoram, phlox, nasturtium, escallonia, cone flower, aster, sweet rocket, lobelia and herbs including chives, thyme and mint.

:: Information: Big Butterfly Count takes place from July 20 to August 11. For details go to