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An industry legend, Sam McKnight was Princess Diana’s favourite hairdresser and is the man everyone from Nicole Kidman to Sienna Miller and Jodie Comer has on speed dial before red-carpet appearances. They love his effortless styles and droll sense of humour.

McKnight is also the master of creating modern volume – or, as he puts it, ‘hair that has guts but still moves – not backcombed or hairsprayed to death’. Along with shine, he says, ‘volume is key to healthy-looking hair.’

However, while McKnight acknowledges that, ‘as you get older your hair changes and you lose a little of it’, he adds, ‘it doesn’t mean having to cut your hair short or change your style. The women I work with, like Kate Moss and Cate Blanchett, don’t want to look old, but do want to keep their own look.’

To add youthful volume, he says, ‘we just need to work a bit harder with products and tools or add in layers. It’s about subtle tricks.’ For those of us without access to the mane man, here are his nine volume commandments:

Any greasiness in your hair is guaranteed to make your style fall flat, so a thorough sudsing is key. ‘Lots of people don’t shampoo properly,’ says McKnight. ‘They rush and miss bits, especially around the face, often the oiliest area. Take time to massage in your shampoo and concentrate on the roots.’ We like Bouf Flouf Factor Growth Shampoo (£15, boots.com).

‘Lots of people use dry shampoo to try to create fullness,’ says McKnight, ‘but it was designed to soak up oil and dirt, which then sit there and can make hair heavy.’ He suggests trying a volumising spray at the roots instead: ‘Technology has moved on and these weightless yet powerful formulas give strands guts while also delivering care.’ We recommend Color Wow Raise The Root Thicken + Lift Spray (from £10, spacenk.com).

‘Any heavy product will kill volume,’ says McKnight, ‘so don’t use a rich hair mask before an event.’ Creams and oils can also weigh down hair, so, as you get older and your hair finer, switch in lighter products. ‘If you have curly hair, trade your oil for a balm. For everyone else, the texture you want is dry and airy.’

Drying your hair with your head flipped over is another old-school technique McKnight deploys. Blasting strands with a hairdryer the opposite way they grow causes the hair to stand away from the root and gives it a volumising lift. McKnight likes to use a YS Park Paddle Brush (£34.95 plus VAT, chrisandsons.co.uk).

McKnight gives fine hair a volumising lift by using a comb to grab hair at the roots, then lifting it up and away from the scalp while directing hot air from a hairdryer upwards at a 90-degree angle.

It took McKnight two years to convince others in his company that he should design a hood dryer. I can see why, I tell him. The 1950s-esque contraption, which fits over rollered hair and attaches to a hairdryer to circulate hot air, looks old-fashioned. He laughs: ‘But it works and is an easy way to a big, bouncy blow-out. The supermodels I worked with in the 80s and 90s knew it!’ The Big Set (being trialled by You’s Rosie Green with McKnight, £30, sammcknight.com) includes a hood, 18 Velcro rollers in three sizes, plus clips.

‘Allowing your hair to cool after styling is important as it locks in the volume you’ve created,’ he says. ‘People often rush to muss up their hair or get out of the door, and this is when their style falls flat.’ If your hair is in rollers, leave it as long as you can (at least 15 minutes) to set. McKnight often twists his clients’ blow-dried hair into pin curls, which he clips up while they have their make-up done.

‘Be careful with face cream around your hairline,’ says McKnight. ‘It can travel upwards so your scalp soaks it up and your style falls flat.’

Humid environments will ‘make hair collapse’, says McKnight. Avoid saunas, long hot baths and showers after styling your hair.

We’d love your help to choose a winner in the YOU Beauty Awards. Tell us your top beauty buy at mailplus.co.uk/awards and the one with the most votes will receive our Reader’s Choice Award in YOU’s beauty issue, published on 26 April.

As a thank you for voting, you’ll be entered into our prize draw to win an overnight stay at the stylish Nici hotel in Dorset. The winner and their guest will enjoy a sea-view suite, dinner and a 60-minute spa treatment, plus use of the hotel’s facilities, which include a heated outdoor pool, spa with indoor pool, Jacuzzi, steam room, sauna and relaxation room (thenici.com).

Ten runners-up will each receive a YOU Beauty Spa Box, worth £218. Filled with luxury treats from brands including Neal’s Yard Remedies, Aromatherapy Associates and Malin + Goetz, it’s the perfect edit for a pampering night in.

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