Littlestone, thank you for that. Ironically, your bete noire, "irreversibility", was one of the reasons EH rejected grouting at an early stage, whereas they have expressed no such objections to tunnelling!

It's a sad fact that all options are going to be irreversible. However, your yardstick is still perfectly valid: a small amount of irreversible intervention is preferable to a large amount. On the basis of what's so far been published, that entirely rules out tunnelling in favour of either grouting or leaving it alone. It'll need some remarkable paperwork to prove otherwise.

You ask: are there "definite plans" to tunnel?
All I can do is say that's how the wind seems to be blowing – and to point you to the evidence: the widespread published enthusiasm for the research opportunities that tunnelling alone would bring, the assertion that EH has a "moral duty" to re-tunnel in order to correct Atkinson's omissions and the fact that the Committee has plainly said tunnelling is "preferable".

Is this enough for "the hundreds of conservators belonging to the United Kingdom Institute for Conservation" to start to raise their voices publicly? My feeling is that it is now, not when a plan is formalised, that their voices are most needed and effective. The matter is still open for debate and will be much harder to influence later. I feel the same way about archaeologists in general. I'm sure vast numbers of them will stand up and be counted in public when the time comes, and know that many are already supportive privately, but isn't it now that the alarm bells should be rung?