9th February 2017

Tam Dalyell was a parliamentarian for 43 years and for 36 of those years he was a columnist for the New Scientist. He was a parliamentary voice for issues of concern to environmentalists, from whom he would often seek information. His most important achievement in this respect, and one recognised in most obituaries, was to save the island of Aldabra in the Indian Ocean, home to such endemics as the giant tortoise and flightless rail, from becoming an air base. He also became concerned about the effect of remedial timber treatments on bats. Well-briefed by Bob Stebbings, he rose in the House to ask whether it was not time that the major treatment companies stopped killing bats in their roosts. That single intervention set a ball rolling that eventually led to the banning of chlorinated hydrocarbon insecticides and fungicides from use in such treatments.

In the 1970s and 80s, mortgage lenders made treatment of wood-boring beetles and timber-rotting fungi in the roof timbers of a house a condition of a loan. Roost visitors had reported finding dead bats in roosts which had been treated with dieldrin or lindane (to kill wood-boring beetles) and pentachlorphenol (for beetles and timber-rotting fungi). The timber treatment companies applied the chemicals at far higher concentrations than was necessary, and provided 20 year guarantees of efficacy. The bats returned to their maternity colonies in spring, roosted on the treated timbers, ingested the chemicals when they groomed their fur and died as a result. Soon after Tam's intervention, I sent the relevant section of Hansard to Rentokil, the market leader in remedial timber treatments at the time, with a draft contract (for £6k) which would involve working with the company to find a method of treating timber which did not result in the death of bats. Rentokil quickly sent its director for Scotland to Aberdeen University and his only concern was to establish whether Dalyell was referring to his company. He said he couldn't possible commit Rentokil to the level of expenditure that I had suggested. I turned to Vincent Weir who provided the funding for Susan Swift and me to carry out a series of experiments which showed that pyrethroids, which were equally effective insecticides, did not result in deaths of bats. The industry refused to accept these findings on the grounds that we had not allowed our bats free flight. MAFF (DEFRA's predecessor) set up an 'Ad-hoc working group on bats and remedial timber treatments' consisting of bat researchers, conservationists and industry representatives which met bi-annually but still failed to persuade the industry to change its practices. Eventually MAFF agreed to repeat the Aberdeen experiments in flight cages at NERC's Monks Wood Experimental Station. Ian Boyd (now DEFRA's Chief scientist) led the research, which confirmed the Aberdeen results but at an order of magnitude greater expenditure. The industry had no alternative but to accept the results. The lethal chemicals disappeared from the market, and were eventually banned altogether by EU legislation. The fact that Rentokil was sued by an operative who had suffered ill effects from the treatments also hastened their demise.

In subsequent years Tam often became concerned about such bat issues such as White Nose Syndrome or emergent viral diseases such as Ebola, and would write or telephone for a briefing. We need more parliamentarians like him.

Paul Racey

February 2017