Why the tax year starts 6 April: Further calendar pains

Following the saga about dates, times and timezones and times and clocks in computer systems...

I was reading the Wikipedia article on Robert Hooke, and noticed this horrifying footnote about the date of his death:

These dates are according to the Julian calendar, which was still in use in England at the time. His date of death raises an additional complication: formally the civil year began on 25 March although common practice then as now was to start the year on 1 January. Thus his legal date of death was 3 March 1702 but was 3 March 1703 according to common usage and as shown here: according to the dual dating practice at the time it would be recorded in church records as 3 March 170⁠2/3⁠. Wikipedia follows the convention adopted by most modern historical writing of retaining the dates according to the Julian calendar but taking the year as starting on 1 January rather than 25 March. (According to the Gregorian calendar that was used in most of Europe, he was born on 28 July 1635 and died on 14 March 1703. The deviation between the calendars grew from ten to eleven days between his birth and his death because the Julian calendar had a 29 February 1700 but the Gregorian calendar did not. For a more detailed explanation, see Calendar (New Style) Act 1750.)

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