A small number of BT lines dropped and reconnected at 12:15. This does seem specific to BT and we're asked them to investigate. The lines did reconnect a minute or so after.
BT say this was due to a ' transmission incident' at FARADAY exchange, saying: "Loss of service to 47 x 100GigE, 4 x 40 GigE, 138 x 10GigE, 1 x 1 GigE and 1 x STM-64 circuits. {Total 6291 GigE}. Suspected fibre disturbance however, unable to confirm."