Prince Charles expressed concern to former Prime Minister Tony Blair that retailers had farmers in an “arm lock” over milk pricing, the ‘black spider memo’ letters have revealed.

The letter, sent to Blair in September 2004, is one of 27 published today revealing correspondence between Prince Charles and a number of government departments.

In the letter, Prince Charles revealed he had mentioned to Blair “the increasing problems affecting the dairy sector.”

Describing the then Office of Fair Trading as “one major problem” that was “becoming a serious obstacle to developing a serious obstacle to developing dairy co-operatives of the necessary size and influence”, he wrote: “Unless United Kingdom co-operatives can grow sufficiently the processors and retailers will continue to have the farmers in an arm lock and we will continue to shoot ourselves in the foot!”

In subsequent correspondence five months later, Prince Charles addressed the issue again.

“There is no doubt that the dominant position of the retailers is the single biggest issue affecting British farmers and the food chain, and if it is not dealt with all the other good work which has been going on risks becoming virtually useless,” he wrote.

He went on to support the idea of the formation of a voluntary buyers charter, as well as an “independent arbitrator to be appointed to deal with individual complaints in an entirely private way”. He also proposed someone who he said “would have all the necessary skills for the role”, though the name has been blanked out of the published letter.

In reply a month later, Blair wrote he had “on occasion expressed precisely the concern about retailers ‘arm lock’ on suppliers that you express so well” and acknowledged that “after something of an improvement things have recently got worse”.

An OFT report was published days before the letter was sent, and though Blair admitted he would “not pretend the report is earth-shattering in any way”, wrote that he hoped it would “keep the issue firmly open” and acknowledged the case for a buyers charter.

In the same set of correspondence, Prince Charles also urged Blair to “look again at introducing a proper cull of badgers where it is necessary”.

“I, for one, cannot understand how the “badger lobby” seem to mind not at all about the slaughter of thousands of expensive cattle, and yet object to a managed cull of an over-population of badgers – to me, this is intellectually dishonest,” he wrote.

Other concerns raised by Prince Charles in the correspondence included greater support for beef and hill farmers, as well as British produce – especially through public procurement.