A number of fibre cables from the Exchange and bRAS start to run North from this small grass area just down the road towards the Centre MK and SMBA Bradwell Abbey Exchange.
A fibre cable running to the Bank of England runs under one of these network chamber covers using dark fibre provided by Zayo (formerly Geo). 186k was taken over by Geo Networks and further by Zayo, so it’s most likely under those 186k covers.