I went for recce from the Ireby side on Saturday. I got as far as the squeeze, but I didn't get through. I don't know whether this was because I'm too big, or because the horrors of South East Passage meant that I was ready to turn back anyway. You know how it is, if you are already feeling a bit out on a limb, then any obstacles become much harder.
South East passage is quite intimidating. The first section is a tight, flat out, 6m long, low airspace duck over cobbles. My ribcage was wedged between the roof and the cobbles, and it wasn't easy to find the tallest section of passage - the roof is flat, but the uneven floor is concealed by very muddy water. I did it face down, and got a mouthful of water and mud at one point. I've since heard that it is easier to do it on your back. Beyond the duck is a lengthy section of flat-out wriggling through a small and very muddy tube (the 'Border Control'?).
I would recommend anyone contemplating the through trip to check out the Ireby side first, especially if there is any uncertainty about the water level in this duck. You really wouldn't want to get all the way through from Rift, past a one-way squeeze, to be faced with a serious and unfamilar duck that may or may not be passable.
At present, I don't think anyone knows whether the duck is simply going to fill up as soon as the current dry spell finishes. Or whether it will get blocked by stones after the first flood.
Much respect to the diggers for forging this link. Lets hope that it is not too transient.