Those Poms really think that Greenwich is the centre of the universe.
Mostly, the June Solstice occurs in Sydney on June 21 but on the year preceding a leap year it slips to June 22 before the leap year resets it back to June 21. Roughly speaking, the Earth takes ~365.24 days to orbit the sun, hence the Gregorian calendar attempts to keep the calendar in synch with the seasons by skipping the leap year every 100th year (..except every 400th year..you may remember that 2000 was a leap year).
As such, the year 1903 hadn’t had a leap year for 7 years and the solstice in Sydney slipped all the way to June 23. This was also the year that Edward VII was proclaimed Emperor of India. How are those poms, eh?
Anyway, as a quadrennial event a June 22 Solstice is woth celebrating on the BoTF in the traditional manner.