The 1975 PSP Act gave the Government wide-ranging controls over field developments, depletion, and conservation of production. Field development plans had to be approved by the DEN, and, where production had already commenced, temporary consents were given until plans were submitted and approved. Limitation Notices were to be issued at the same time indicating the maximum cuts (or increases) which the Secretary of State could require. Twelve fields were covered by the temporary consents, and in the event ten of them, including large ones such as Forties, Leman, Indefatigable, and Hewett, were subject to six-monthly consents. It was recognised that it would be very difficult to enforce major changes to the development plans for these fields, and the DEN concentrated its efforts on assessing the plans for new fields. For fields which were commercial in 1976 the Limitation Notices specified the maximum cut at 22% in the first year permitted by the Varley Assurances with a reducing percentage through field life. Exceptions were made for three fields (Piper, Claymore and Thistle) where undertakings had been made by the DEN to the banks which financed their development to limit any cuts to no more than 20%.