Jill's limousine was delayed by heavy traffic on the way to the glittering Hollywood ceremony last weekend.
The doors were just closing as she dashed up the red-carpeted stairs.
She had been in her seat for only a few minutes when she heard she had won an Academy Award for her set design work on the British hit Shakespeare In Love.
Jill, from Lavant, near Chichester, said: "It was a magic moment and I almost missed it.
"We had been in our seats for literally five minutes when we found ourselves being catapulted on to the stage."
Jill, who won the Oscar with Martin Childs, shared the spotlight with fellow Oscar winners Gywneth Paltrow (best actress) and Dame Judi Dench (best supporting actress) as Shakespeare in Love cleaned up.
She returned home yesterday clutching the Oscar, for a champagne lunch at the home of friends Torquil and Susan George in the village of West Stoke, near Chichester.
Jill, nominated under her professional name of Jill Quertier, said: "It has been the most amazing week and people have been so kind and generous. I came home to find lots of cards and messages.
"The Oscar is wonderful and I have been carrying it around with me everywhere."
Jill, whose previous screen credits include set design on Gandhi and for the television series The Far Pavilions, is waiting to see what her next project is to be.
But she added: "Some people have actually said that you don't work for 18 months after receiving an Oscar because people assume you are going to be busy or too expensive."
Converted for the new archive on 30 June 2000. Some images and formatting may have been lost in the conversion.
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