Just to keep you updated - following a fibre failure on Monday, BT thought they had fixed it Monday night, but it was down an hour later. They thought the fixed it yesterday, but our monitoring shows the fibre is still not right and we await an update.
In the mean time traffic is using the remaining 3 LNSs as expected.
BT think it is fixed - we are monitoring for 24 hours before putting traffic on it.
Looks like Bt finally fixed this last night, and we are monitoring it