Has Spring Sprung?

The (probably not so) old ditty goes:

Spring has sprung,
The Grass is riz,
I wonder where the birdy is.
The bird is on the wing;
But that's absurd,
The wing is on the bird.

Any more known?

But seriously (only slightly more so) when does spring actually begin?  My understanding is that it traditionally starts on the vernal equinox, which is on the 21st of March, although the popular press now seems to favour the 1st of March; perhaps that's just if there is a shortage of news or a surfeit of lambs to photograph - YJ will tell you how, as a cub reporter, he was the one sent out with the photographer to throw an unwilling lamb into the air to be pictured as if it were leaping, full of the joys of spring.

But checking (now he's starting a paragraph with a conjuntion!) on http://www.canterburyweather.co.uk/sun/ukmap.php?d=13&m=2&y=2010 I now find that the equinox in Manchester was on 17th March (sun rose 6:18 set 18:17) so when did spring start?

Moving on, my spring starts when the clocks change and I can get onto the fells in the light after work.

Would anyone like to celebrate this with me by joining me UTUP on Maunday Thursday 1st April? I'll be there.

By the way, (or even, by the wayside) I saw my first trace of green on a hawthorn hedge this morning, perhaps that means that spring really has sprung.