Then a day or so later my wife Sarah was giving the grass it's first cut of the year (she wanted to, honestly!) and she found another egg, this time completely intact. She was certain it wasn't there when she started, although the grass was a little long in places, and so we presumed it had fallen out of the sky, favouring the Magpie or Crow scenario.
At around 4cm long, the eggs are larger than most common eggs I've found in and around my garden over the years, and they are also a smooth featureless white colour. They might not even be both from the same bird as the broken one on the left is a little longer and a bit more pointed at the ends than the one on the right, which is ever so slightly pinker in colour.
My best guess at the moment is that they belong to a Wood Pigeon, or perhaps a Collared Dove but I'm open to suggestions for correctly identifying them.
If you've any ideas to which bird these eggs belong and how they ended up on our back lawn, we'd be interested in hearing from you - just click on 'comments' below this post and, after writing your message, use the 'Anonymous' identity to log it for speed if you like.