The wedding dress stopped being clothing long ago and became a budget line. Here it takes a sum that for most families means giving up something else. Which is why it is worth looking at what the women whose photographs have been cited as the standard of elegance for seventy years actually wore.

Mia Farrow, 1966. She married Frank Sinatra in Las Vegas on 19 July. The dress for the ceremony came from her own wardrobe - ivory, with a bow at the waist and a short jacket with decorated buttons. For the celebration she wore a lace model. The price of that second dress was 27 dollars. Her explanation is one sentence: she found out the day before that she was getting married, so she wore what she had.

Audrey Hepburn, 1954. For her wedding to Mel Ferrer she wore a midi with gathered sleeves, gloves and a crown of flowers, signed by Pierre Balmain. Her son later said it was most likely an existing, ready-made model, because the wedding was arranged in a hurry. Balmain is a name that still means money, but the piece was not commissioned for the occasion - it was taken from what already existed.

Brigitte Bardot, 1959. For her wedding to Jacques Charrier she wore a cotton dress in pink and white gingham, the work of Jacques Esterel. Cotton. Checks. In 1959, when a wedding dress meant satin and floor length. That is not thrift - that is a refusal to play by the rules.

Marilyn Monroe. At her first wedding, in 1942 to James Dougherty, she wore a simple white silk dress and a borrowed veil. At her wedding to Joe DiMaggio she wore a dark brown two-piece suit with a white fur collar, bought at a department store in San Francisco.

Elizabeth Taylor, 1950. This is the opposite example, and that is exactly why it matters. At 18 she married Conrad "Nicky" Hilton in a dress by Helen Rose, MGM's studio costume designer - ivory satin, pearls, embroidery and a veil of silk tulle. It cost around 1,500 dollars in the money of the day. At a Christie's auction in 2013 it sold for 190,000 dollars.

So an expensive dress really can return many times over - if you are Elizabeth Taylor and if somebody sixty years later is willing to pay for your name, not for your dress. For everyone else the arithmetic is simpler: Mia Farrow's 27-dollar dress is on the same lists as the one that fetched 190,000. The difference is made by what is remembered from the day, not by what was paid for it.