FALLING exactly nine months before Christmas, Lady Day commemorates the Annunciation – the day the Angel Gabriel announced to the Virgin Mary that she would become the mother of Jesus, writes Judith Field.

This epoch-changing moment has been captured by artists such as Leonardo da Vinci, Botticelli, Dante Gabriel Rossetti…and here in Cornwall by Frank Pearson, son of Truro Cathedral architect John Loughborough Pearson.

Historically, Christian festivals set the rhythm of both secular and spiritual life. Lady Day (March 25) was New Year’s Day — the first of four ‘quarter days’ that divided the year, the others being St John the Baptist (June 24), St Michael and all Angels, or ‘Michaelmas’ (September 29) and Christmas Day itself.

On these days, taxes and rents were due. For instance, from the 1100s to the 1800s, tinners came to stannary towns like Penzance, Helston and Truro on quarter days to pay coinage to the Duchy of Cornwall – a tax collected in coin-shaped pieces of refined tin.

Lady Day had special significance in rural areas. Labourers entered into new contracts with farmers at Candlemas (February 2), and March 25 was the day that workers moved to their new employer. Since cottages were tied – they went with the job – everyone had to move on the same day, in and out.

Thomas Hardy described the scene in Tess of the d’Urbervilles: “At length it was the eve of Old Lady-Day, and the agricultural world was in a fever of mobility such as only occurs at that particular date of the year. It is a day of fulfilment; agreements for outdoor service during the ensuing year, entered into at Candlemas, are to be now carried out.”

What did Hardy mean by “Old Lady-Day”? Surprisingly, our calendar is quite new. Up until 1752, we used a calendar introduced by the Roman Emperor Julius Caesar in 46BC. But the calendar was slightly off, which meant that over the centuries, it gradually fell out of sync with the seasons.

So in 1752, we took the plunge and switched to the Gregorian calendar instead. This radical change meant jumping forwards 11 days to catch up with the Gregorian date, and New Year’s Day was moved from Lady Day to January 1.

All this meant that March 25, 1752 and April 5, 1753 were the same day, and with an extra one day adjustment in 1800, that day is now known as April 6. To avoid yet more complications, they decided to leave the start of the tax year where it was rather than move it to January 1, and the two have been separate ever since.

Religious feast days like Lady Day were exempted from the upheaval, though, so it is still celebrated on March 25. A special Lady Day service will be held at Truro Cathedral at 11am that Tuesday, followed by coffee in the Chapter House.

In a good week for mothers, Mothering Sunday follows on March 30 at 10am, including distribution of traditional spring posies. For details, visit www.trurocathedral.org.uk