This comes from me reading an article with reference to Lady Day and the year. Member Frances H. explained it and then I was off looking for more…
Lady Day is on 25 March. It’s the Feast of the Annunciation when the Angel Gabriel visited the Virgin Mary.
It’s the first of four traditional quarter days in England, Wales and Ireland. Midsummer is on 24 June. Michaelmas is 29 September, and Christmas the 25th. These dates are when servants were hired, school terms started and rents were due. They were +/- 3 months apart and are close to the two equinoxes and two solstices.
Another thing to be aware of is the regnal year. That’s the year in the reign of a monarch. You might see something referred to as happening in the 7th year of a monarch’s reign and no real date was given. There is a calculator you can use to figure out the actual year.