They're traditionally one of the first signs that spring has sprung. But a daffodil's already in bloom in Nigel and Jackie Sisson's garden.

Retired publishing executive Mr Sisson, 80, and his 75-year-old wife have no idea why the determined daff has appeared so early outside their house in Dersingham.

'We've got daffodils that come up every year,' said Mr Sisson. 'This is self-seed, it's a lone one, for the last five years at least it's been early.

'It's in a raised bed that's not particularly ssheltered, not particularly exposed. I can't account for it - perhaps your readers can.'

Traditionally, the UK daffodil season is between March and late April, with the flowers' biggest markets being Mothering Sunday and Easter.

The first daffodils usually come from Cornwall, where the flowers are farmed because of the mild climate.

At the beginning of 2010, the flowers were spotted as early as New Year's Day when dozens were discovered in Brixham, Devon.

Eoin Redahan, from the Royal Horticultural Society, said: 'It's slightly unusual but not unknown for daffodils to be flowering at this time of year. It depends on the variety and how mild the weather's been.

'Daffodils can flower throughout the year. people associate them with march and April but different varieties can bloom earlier than that.'