One of the most intriguing things about Flickr is the concept of 'interestingness' - an arcane formula based on, among other things, the number of times a photo has been viewed, the number of groups it has been added to, the number of external-to-flickr links and the speed at which these and other statistics have been clocked up.
Discussions about how the algorithm is constructed are endless and, so far, fruitless. But at any given time, the top rated 200 photographs posted each day are displayed on the Explore page.
Some flickr members have never hit the Explore page; some are there almost every day. Some people are pleasantly surprised to find comments from people who stumbled across their work on the Explore page; others work tirelessly to try to second guess the formula and maximise the number of photos in this not-so-exclusive club.
A number of third party tools exist to allow you to check how many photos you currently have in Explore - the rankings are dynamic, so you can mysteriously appear (or, more likely, disappear) months after your photo was posted. I have contacts with 40 or more Explore photos. My peak so far is a feeble 10 - though a couple have occupied the coveted Number 1 spot, albeit briefly - and my average more like 8.
To give me an excuse to write something in the blog, I've decided to share a little about the background of those that have appeared there - and those that have stuck around.
The first is unique among my pictures by virtue of having appeared no less than 3 times in different forms and of having spent a respectable amount of time at Number 1 in its original form.
It was one of a batch of pictures I took on the walk between Gray's of Westminster and my office in Battersea the day the D200 was launched.
The first version - uploaded within half an hour or so of being taken, along with 50 or so 'snaps' and test shots - attracted a fair amount of attention (as did all the others) from soon-to-be and prospective D200 owners.
It was a couple of days later, though - when I ran it through Nikon Capture and uploaded a warmer, better exposed and slightly cropped version - that it really took off.
Undoubtedly people were still stumbling across it in their unquenchable desire to find any D200 images anywhere on the web. But the comments suggest it had at least some merit in its own right.
I didn't really do much to it - lifted the exposure over all and the shadows a little more; warmed the colour temperature a little and toned down the glare from a truck's tail lights. Subsequent versions have had different crops and there has been a black and white version. Most have been well received and several have made the Explore page, but none have come close to the original.
Over the last 18 months I've returned to that area of the Embankment several times to capture the converging perspective of the trees and street lamps at differnt times of the year and at different times of the day but nothing else has come close to that first winter sunset.
And now the office has moved West - away from the river - so I'll have to find inspiration elsewhere.