Well, both Essex and Hertfordshire were some of the largest remaining strongholds for SOX in the south east. There aren't many councils in the south east now that haven't been subject to some form of PFI programme or considerable replacements, whether partial or all out. The good news is that, even after Hertfordshire's A roads and a few small town centres in Essex are converted to LED, the vast majority of street lighting in both counties will still be SOX.
The Essex LED trial is a drop in the ocean - representing just 1.3% of Essex's street lighting stock,
and the county is still installing new SOX casual replacements in existing SOX-lit streets. But having said that, new SOX casual replacements have definitely got thinner on the ground this year compared to 2013, with SON now the light source of choice in Essex for casual replacements. If I was a betting man, I'd say that somewhere between 75 and 80% of the street lighting in Essex is still SOX, and that will trickle down by perhaps up to 2% a year for the forseeable future. In 40 years time, SOX may be as thin on the ground in Essex as MBF is now.
Hertfordshire is pushing the boat out a little further - all the street lighting on the county's A roads represents 11% of their lighting stock, so it represents quite a loss (especially as Hertfordshire's A roads are full to the brim of old SOX lanterns). Hertfordshire still has an enormous SOX legacy, and in the absence of a PFI or a comprehensive LED replacement programme, such a legacy will ordinarily take decades to wipe out under normal circumstances. Having said that, it looks like Hertfordshire are embracing LED with greater enthusiasm that Essex.