Actress Krysten Ritter.

Krysten Ritter arrives at Late Show with David Letterman in a head-turning hue. Photo: Getty Images

It all started with a cardigan. A yellow cardigan my sister inherited from one of her daughters. As soon as I got it on my body, I knew I needed a yellow cardigan more than anything in the world. A yellow cardigan would go with everything I own and make it all look fresh and new. Even my tired old face.

Then I realised I also needed some yellow shoes. What could be more cheery? Then everything started to look better in yellow, going right across fashion and into homewares and stationery.

The moment I first saw those genius old-style phone handsets that you plug into your mobile phone so you don't turn your brain into a frittata, I knew that of all the myriad cool colours and finishes available, it would have to be the shiny yellow one for me.

It's my latest colour crush, inheriting the throne from a line that goes back through grey, navy, cornflower, chocolate brown and bright pink to head-to-toe black. When you're in the throes of such a tonal passion, absolutely everything from undies to napkins has to be better in that colour.

I know it's not just me who goes through these colour changes because there's a whole industry of people dedicated to working out which ones we're all going to be mad about next so they can tell the people who make undies and napkins and Pop phones well in advance. Their skill - and they get paid loads for it - is to know before we do, and there's a whole science to it, apparently.

Although I'm beginning to wonder if they're quite across it because I can't find a yellow cardigan anywhere. There are quite a few yellow shoes about, though, so that's a good sign. Clearly it's not just me; there are other people out there feeling it for the sunshine shade, and the relevant merchandise can't be far off hitting the shops. Can't happen soon enough for me.

Meanwhile, there are a couple of other colours I'm starting to feel the love for. One is purple, which is easy because that's a big fashion trend for this season, so it's all out there.

I've already got my purple shoes and a great pair of the new print pants with a lot of purple in the mix. And I've had the purple cardie a while already. I'm sorted on purple. I even have some napkins from the last time I loved that particular hue a few years ago.

So what's any of that got to do with this picture of actor Krysten Ritter? Dark bottle green is what. Or would you call it holly? Whichever, dark green is another - and I think most surprising - colour to come back into my personal rainbow.

I haven't come across dark green for years; plenty of forays into mint, sage and other softer tones, but now the full school-uniform shade looks right again. I think the last time was 1986, but even then, I never wore it in a dress, especially not an occasion frock such as this one. Knitwear, tailoring … great. Never a dress. But I think this looks really sharp, mainly because it is so surprising.

A colour-popping dress in red, orange, pink or purple is one thing - and, come to think of it, I actually own dresses in all of those colours - but there's something really unexpected about a dark-green dress.

The style of it is nothing out of the ordinary - it's a pretty simple fitted frock - but the offbeat colour makes it exceptional. Which all goes to show: you can make a big impact with very little effort if you just make a bold statement with one part of the look.

And adding a pair of shoes that combine pointiness with a leopard print is never going to hurt either.

Maggie Alderson's new novel, Everything Changes but You, is out now.