According to Elexon:
"Since 6 April 2014, all Meters within Profile Classes (PCs) 5-8 must be an ‘advanced’ Meter capable of being read remotely and recording Half Hourly (HH) consumption. However, there is no mandate to settle these HH capable Meters on a HH basis.
P272 proposes to make HH Settlement mandatory for all Metering Systems within PCs 5-8 (where capable metering has been installed), as the Proposer believes that the use of Non Half Hourly (NHH) data is not as accurate and masks individual customer behaviour."
"P272 will be implemented on 1 April 2017."
That's the official word, but what does that really mean?
Basically, anyone with a "Maximum Demand" 05-08 profile class meter, will see a slight change to the way that they're being billed as their meters will provide half-hourly data to the network instead of being read manually by a chap with a torch. This will allow suppliers to balance and monitor usage more actively and efficiently, reducing the risk of estimating usage on these large meters and providing more accurate billing.
You should receive information both from your supplier and from your Distribution Network Operator (DNO - the guys who actually get the electricity to your premises and manage it) informing you of the changes. In terms of your billing, you will see a few more lines of information, as the various aspects of your charges will be split out for you to see instead of you just having a rolled up standing charge, a lot like having an itemised phone bill. You should also benefit from more accurate billing and, if you're not happy with the way that you are being billed, will be able to choose your own Data Collector (DC) and Meter Operator (MOP).
All in all, this should result in better billing and a more efficient energy network for mid-market electricity users.