Some people buy vintage because it's cheap. Like the bargain-hunters in London's East End who queue round the block to buy by the kilo or £1 bag.
Others like antique buttons, quirky fabrics – and knowing that no one else will turn up in the same dress.
Vintage enthusiasts at the Goodwood Revival gather near Chichester every September for the glamour and theatricality of stepping back in time.
But Tess also imagines the people who used to wear the clothes. She remembers her grandmother's stories about rationing and shortages. She thinks back to what it must have been like getting ready for a dance – Glenn Miller, lips stained with beetroot juice, seams painted on the backs of your legs when there were no stockings left to buy.
If you wear vintage, you feel a sense of solidarity with women in the past. I used to have a black 1940s day dress that looked brilliant with bright red nails. Whenever I wore it, I thought of the original owner. What did she look like? Vivien Leigh? Ingrid Bergman? Lauren Bacall?
Other favourites were a Victorian corset cover (a sort of fitted bodice in cream calico edged with lace) that I used to wear with jeans, a 1930s peach silk petticoat that could just about pass as a party dress, and a waist-length green cardigan that looked as if it might have been hand-knitted in wartime Britain.
Every time I wore these vintage finds, I thought about the women in the past who had loved them first. The clothes were being given a second chance, a new lease of life. (Not always in ways the original wearer would have understood. But I hoped the petticoat-owner would forgive me.)
You have to accept that vintage doesn't always last, especially if it has been worn a lot the first time round. I remember the 1960s pink satin slingbacks – pretty tatty when I bought them – that I managed to trash in one night. Trailing back in the early hours as the sun came up, I felt a strap break, then a heel.
In the end, when I could hobble no more, I took the shoes off and walked barefoot. At my front door, I upended them into a litter bin attached to a lamppost. There they were, balancing on the rubbish in the rosy dawn light, stiletto heels pointing to the sky.
It should have been sad. But it wasn't. These were party shoes. They had been danced to death. It was the right way to go.
Like Tess in my novel, I buy vintage because it's cheap, unique, and beautifully made.
But mainly because I'm a romantic.
Marianne Kavanagh's debut novel For Once in My Life is published by Text at £10.99.