Tensions were riding high at the Royal Academy of Art's 1832 Summer Exhibition. Constable was unveiling his masterpiece 'The Opening of Waterloo Bridge,' with its moody shadows and scarlet-topped barges bobbing on the Thames, which had been thirteen years in the making. Adjacent sat Turner's smaller and rather watery-grey 'Helvoetsluys' seascape. When Turner saw the oils hanging next to each other, he marched up to his own canvas and planted a single daub of red paint in the middle of the rolling waves (he later modified it to a red buoy) to draw the eye, unequivocally, to his work. It succeeded. On seeing Turner's improvisation, Constable declared, 'He has been here and fired a gun.' 

Such is the power and effect of the merest hint of red in a painting, or, for that matter, a room scheme. As Neptune's creative founder, Emma Sims-Hilditch, explains, 'I love the warmth that a touch of red can offer – be it a lampshade, a cushion, or even a red-painted picture frame or picture mount. But it also acts as a focal point: your eye will naturally be drawn to a hint of red in an otherwise more muted colour palette.' 

And while most interior designers would agree that neutral colour schemes feel harmonious, calming, and welcoming, they would also suggest such rooms need depth to make them interesting and cosy. A pop of warm red in the form of just one vase or cushion, or even a stripe on a cushion, can be all it takes to turn a space from ordinary to something special.

This is because red is an 'advancing colour' – it appears to come toward you  – which is why it's so successful at creating a sense of depth when used against cooler, receding colours and neutrals. 'It could be as simple as some red spines on a bookshelf,' suggests Emma, who also runs interior design company Sims Hilditch. 'The merest hint of red makes the other colours stand out more. It's a bit like red lipstick on a face – it brings things to life. Or in nature, a robin redbreast in a snowy scene has the same arresting and beautiful effect.' 

Used to excess, red can feel overwhelming in a space, but according to Emma, the 'daub' of red technique can be introduced into most rooms of the home effectively – a deep red feature chimney breast in a sitting room, an elegant red bookcase in a study. Or even in a kitchen: 'I particularly love using our Burnham Red shade as a contrast. Consider painting bar stools red against kitchen cabinetry in Alpine Blue, Shell or Shingle.' Indeed, Emma has used the technique in the Cornish cottage she shares with her husband and Neptune co-founder John Sims-Hilditch – the bright red hull of a model sailboat pings amidst the gentle colour palette of the sitting room. Turner would have been delighted.