History
Boulogne does not appear on BT site lists (unlike Fiennes) however it has been included as the "end point" of the mid-1980s cross-channel link from Archers Court. The actual site is not confirmed but understood to be Mt Lambert, an existing broadcast and communications facility.
A list of BT equipment suggests the link was 140 Mbit/s on 11 GHz using Thomson CSF equipment and entered service in 1986.