Mr. Parus has already done all the hard work with this post, so I'm free to ramble about the things I liked. This trip was an object lesson in birding by sound - most of the stuff on my list for the day was heard before it was seen, if it was seen at all.
Saw my first ever Whitethroats (being new to birding is great - everything's a tick!). They are cool, but very loud. The song snippet on the RSPB website doesn't do them justice at all. Generally quite easy to see though. Tick.
Saw my first Willow Warbler. The song is quieter than the Whitethroat but very distinctive in its own way, with the descending scale of repeated notes. The RSPB do a much better job with this one. Tick.
The Cuckoo was easily the best example of a bird heard before it was seen. They're just a bit unmistakable. We were wandering round trying to get a second view of the Willow Warbler at the time, an activity which was quickly abandoned when the Cuckoo song came drifting across the trees. We had an unbelievable in-flight view, and just in case there was any doubt, it started calling in flight as it went about our heads. Tick.
Skylarks were extremely vocal and the only things close to matching the Whitethroats for volume and persistence. Good flight views again. And 4 displaying Lapwing were making their strange computer-like calls as they rolled and tumbled through the air, divebombing an unfortunate Crow who got too close.
This was my first trip to that side of Ingrebourne, and with the promise of Yellow Wagtails, Yellowhammer and Wheatear on that patch I'll definitely be trying to get back over there sometime soon.