In the UK all premises with a electricity demand higher than 100kW must have a Half Hour Meter. Half Hour (HH) meters require a MOP contract to be in place.
Note, even if you cannot find any record of a MOP contract in the accounts or legal department of your organisation there is a provision for MOP. As the electricity industry was restructuring, the local distribution companies (North East Electricity Board etc) were acquired during a period of consolidation.
The MOP contracts were transferred. Example in North East England (as NEEB changed ownership) the MOP services were eventually default owned by nPower. These unsigned MOP provisions are referred to as “Evergreen” with a vague extra row on the invoice for metering services.
An Evergreen MOP service is often more expensive than a signed and active agreement. Any organisation is allowed to appoint a MOP and separate the meter charges from the electricity supply charge.