Your "etc etc" isn't very informative the way Drucker at least tried to be.
I've no vested interest in any of this. If someone proves conclusively that March (and now according to you it seems to be "mid March" again a very fluffy term) has a better call on being the start of Spring rather than the first week of February I'll be delighted to be educated.
The "vernal equinox" at which you seem to be pointing now is NOT mid March, but according to google
In the Northern Hemisphere (where most Cork people find themselves) the vernal equinox
falls about March 20 or 21, as the Sun crosses the celestial equator going north.
So the suggestion that the First of March, the first week of March, or even mid-March marks the start of our Spring is mistaken.
Do you want to try again?