John Barstow says oil expansion is a necessity, while David Parker wonders if the prime minister will protect the planet or the fossil fuel industry

North Sea oil expansion is a necessity (Burnham risks first revolt as PM over apparent support for North Sea drilling, 31 July). I state this as an environmentalist – not despite. Oil is a feedstock, not mere fuel. Oil is necessary for the day-to-day maintenance of wind turbines, nuclear plants and rail. Hence oil is part and parcel of supply chains for green tech. A domestic oil base brings such supply chains closer. This also underscores the case for approval of coking coal extraction in Cumbria. Green tech needs high-grade steel and high-grade steel needs coking coal.

There are much better ways of helping the environment, such as more tree planting and stopping plastic waste being dumped into our seas. The carbon sink factor would be helped. A major expansion of the UK’s North Sea oil sector will make a more cohesive UK, complete with more jobs in Scotland and the north of England, including in supply manufacturing chains.

British cheesemakers have struggled to find a use for the 95,000 tonnes of salty whey they produce every year. But researchers may have come up with a solution

Name: Whey.

Age: As old as milk.