Presumably the “wrong sort of water on the line”…
Expect they are blaming Brexit and the French again.
I can understand the occasional SF’s having damp basements but a huge and important service like this should surely have massive sump pumps (plural) so even if one set breakdown there is backup.
Probably french pumps 
Indeed - apparently HS1 are blaming “unprecedented flooding” - not sure where the water has come from as London has had average rainfall for December.
Maybe the Thames sprung a leak.
Looks like the Ebbsfleet bit which is not that far from the estuary but I am just guessing.
You obviously haven’t seen the TV video showing water pouring through the roof at several hundred litres/min and the completely submerged trasck bed. Apparently trains were rfunning through it earlier.
You are correct, I havent seen the video. Sounds like a major tunneling issue from your description.
It looks like a very serious tunnel issue. The section flooding is presumably under the river or under the water table. Water seems to be gushing in where a large diameter pipe goes through the tunnel wall. The pipe looks like a ventilation pipe to me. Why such a large pipe is going straight through the wall of the tunnel in a possibly underwater section seems strange.
Got a link to the video?
Just like Venice without the feckin gondolas
Britain opens fitst lazy river ride to France
It’s good to see Thames Water getting their alibi in pdq. This from the BBC News site:
Nah, its to get rid of the migrants, arrive by boat, leave by lazy river, cheaper than Rwanda.