Lily James parties in the park with co-star Dominic Cooper and pals Billie Piper & Gemma Chan

LILY James knows how to Abba good time — as she parties in the park with Mamma Mia! co-star Dominic Cooper and other pals.

The giggling actress, 31, looked like she was suffering from hay fever.

But it didn’t stop her enjoying a drink with laid-back Billie Piper, 37, who relaxed in shades and a floral dress while puffing on a cigarette.

They were spotted with Dominic, 42, and his actress girlfriend Gemma Chan, 37.

Our exclusive pictures show the Brit Pack actors sharing a picnic and laughing and ­joking as they soaked up the early evening sunshine in North West London’s posh Primrose Hill park.

Lily — who plays young Donna Sheridan in hit ­follow-up film Mamma Mia! Here We Go Again — appeared to regularly blow her nose amid the highest hay fever levels for more than 50 years.

The group quaffed from a bottle of Pimm’s and another of wine.

An onlooker said: “They seemed to be having a great time boozing.

"Lily and Billie in particular were laughing a lot and Billie seemed the life and soul of their little party, although Lily was a bit sneezy, probably from the high pollen count.

“No one really bothered them but people are used to seeing celebrities around that area.”

Lily and Dominic — who played Sky Rymand — won rave reviews for their roles in the 2018 box office smash.

And the pair enjoyed sizzling temperatures like the musical’s Greek island setting for their evening with Crazy Rich Asians star Gemma and singer-turned-actress Billie.

The four are part of the “new Primrose Hill set” in the trendy London enclave.

But they will struggle to live up to the notorious antics of the 1990s originals including Kate Moss, Sadie Frost, Meg Matthews and Liam and Noel Gallagher.

Downton Abbey actress Lily, seen with her hair scraped back and in a black vest-top in our pictures, is said to have rekindled her romance with ex-Doctor Who actor Matt Smith, 37, during lockdown.

The Sun told last month the couple, who split in December after five years, had isolated in their North London home before restrictions were eased.

Their romance was said to have become strained over Matt’s friendship with Claire Foy, 36, his co-star in The Crown.

But a source said: “Lily and Matt kept their house together and when lockdown began, they ended up isolating together.

“It allowed them to reconnect and get back to a good place.”

On Friday Lily was back in the same park with a friend, this time in a black bikini top.

GOT a story? RING The Sun on 0207 782 4104 or WHATSAPP on 07423720250 or EMAIL exclusive@the-sun.co.uk