Looked at some of the COR on my slightly round-about trip to Chelmo this morning. Boxley Lane, from Hellman's Cross, used to be a decent gravel track, but sadly very churned up by 4x4s. The bit I rode was dry-ish, but no fun on fixed trying to avoid pedal strike on the ruts.
On the other hand, the bridleway from Aythorpe Roding to Broomshawbury was mix of overgrown nettley/brambly sections [walked about 200 yards], overgrown grass and cow parsley [rideable], short-grass track and dirt road [not too bad, just a bit bumpy on some of the hoof-churned bits]. There's a nice wooden bridge over the River Roding though. I didn't have time to investigate the section on to Crabbs Green Farm - looked to be gravel farm road, but the right of way is dubious - my OS map has it as white road and 'other route with public access'. All told, probably saves a couple of miles, but will be much slower going...I think the peloton would be happier with Steve's route from Pleshey via Great Canfield.
psyclist - 21:00 is usually our target arrival time - doable with a 19:00 start from Witham.