We’re accustomed to admiring the Princess of Wales’s glossy hair and soft smokey eyes, but we need to give credit to Kate for embracing a different ageless beauty look – one that just happens to use the biggest product in makeup right now.

At this year’s Trooping the Colour, the Princess, 44, showed how she’s been quietly been perfecting the art of lip liner. It’s a product that’s currently enjoying a huge resurgence in popularity, and one that beauty experts describe as vital for women over 40. While a Gen Z-loved contrast between lip outline and lip infill may be hogging all the hashtags on social media, there’s a softer, more wearable version of liner that’s proving equally covetable for mature women. And for one simple reason: it makes older, thinner lips look naturally plumped.

kate princess wales lips
Samir Hussein
Kate’s beautifully defined lip colour at Trooping the Colour

The Princess showed off her subtly-defined pout at the King’s official birthday celebrations in London, where her lip shape looked visibly more defined with liner than usual. Opting for a rose-toned outline, plus a soft, sheeny gloss, Kate’s makeup epitomised the polished, subtly-plumped look women over 40 can’t get enough of.

To get a sense of the appetite for Kate’s lip, look no further than Trinny London’s just-launched Lip Reset Kit. Trinny Woodall’s curated combination of liner and complementary gloss has already sold out on her brand’s own website, as mature women flock to buy a wearable, believable alternative to injectable fillers.

kate princess wales lips
Chris Jackson
Kate opted for a more sculpted and lined lip look

As Trinny herself told GH, ‘Probably the issue I hear most from older women is, “I don’t have a top lip”. And they don’t want to do lip filler, they just want something that they can put on and feel they can wear a lip again.’

Kate’s makeup follows Trinny’s own advised technique for a plumped and flattering ageless lip. As she demonstrated to GH, ‘I put the liner on exactly the shape of my lip, and in the middle, I go straight across. If you emphasise your Cupid’s bow, you actually emphasise lines more.’

Kate’s own liner is the perfect, softly-rounded shape that avoids looking artificially overlined (something that can also risk creating a ‘moustache’ look if the liner is over-dark).

kate princess wales lips
Mark Cuthbert
The ageless lip look is trending right now

Kate’s soft, grown-up type of liner also helps with a problem commonly seen by celebrity makeup artist Gucci Westman, and one she’s experienced herself. ‘Lips lose colour with age, and they just blend into your skin, which is so not happening,’ Gucci tells us. ‘I’m completely committed to lip liner, I can’t be without it. I feel like the older I get, the more dependent I’ve become on lip liner.’

kate princess wales lips
JUSTIN TALLIS
Kate alongside her youngest son, Prince Louis

To recreate Kate's perfect grown-up liner, take a few tips from makeup artist Hannah Martin, who actually did Kate’s makeup on her wedding day.

‘Avoid a lip pencil that’s too orange toned,’ she advised us at a masterclass. ‘That’s when you get ‘spaghetti lips’ where it looks like food stained around your mouth. Use a cool-toned matte lip pencil instead. Clinique’s Nude Honey Quickliner lends itself beautifully to this look.’

For the most flattering finish on mature skin, Hannah advises using a soft, slightly-blunted pencil, rather than anything sharp and scratchy. ‘Keep the lip pencil in contact with the lip at all times and do lots of little strokes, buffing back and forth,’ she adds. ‘This is the way that you get the most soft and blended finish.’

kate princess wales lips
Max Mumby/Indigo
Kate used a matching shade on her lips and cheeks

Once you’ve got the lip shape right, Hannah advises using a small buffing brush to very gently soften the line, then fill in with ‘a soft creamy lip colour, such as a Clinique Chubby Stick… I love the Auntie Apple shade’.

Kate’s makeup also incorporates another trick loved by Hannah. ‘Blend a bit of the same lip colour on the cheeks, too, for a monochromatic look.’

And that’s the word on the lips, for now.