The owner of Geronimo the alpaca which was culled a year ago has said she is continuing her fight to prove the animal did not have bovine TB.

Helen Macdonald called on the new prime minister, who will take office next week, to sack Environment Secretary George Eustice and launch a review into Government TB policy.

Geronimo, which had twice tested positive for bovine TB, was culled by vets on August 31 last year after his owner lost a lengthy legal fight to halt the execution warrant.

Ms Macdonald was campaigning for the destruction to be halted after insisting the bovine tuberculosis tests previously carried out returned false positives.

The veterinary nurse argued the Enferplex test was fundamentally flawed and said Geronimo tested positive because he had repeatedly been primed with tuberculin – a purified protein derivative of bovine TB bacteria.

The alpaca was euthanised after police officers and staff from the Department for Environment, Food and Rural Affairs (Defra) arrived at Ms Macdonald’s farm near Wickwar, South Gloucestershire.

At the time, Defra said initial post-mortem examination tests had found a “number of TB-like lesions” but further tests would be carried out.

Speaking on the anniversary of Geronimo’s death, Ms Macdonald said: “George Eustice needs to go in the reshuffle.

“Boris Johnson could have stopped it and he is just as incompetent and complicit in all of this.

“Will the new prime minister, and it sounds like it could be Liz Truss, have the courage and care enough to form an investigation or find out what been going on at Defra?

“There’s this whole policy of killing animals at the taxpayers’ expense without looking at the science and the lid has come off it and they need to be held to account.”

Ms Macdonald said she still did not know how exactly how the alpaca had died after being removed from her farm and loaded into a trailer and taken away.

“They still won’t tell me how he died, and they still won’t prove to me he walked out of that trailer,” she said.

“They all had body cameras and there was CCTV. If he did walk out that trailer – there is no reason why they can’t prove it.”

She has ongoing complaints lodged with the Parliamentary Ombudsman and the Independent Office for Police Conduct about the operation to cull the animal.

“Everything’s just really slow,” she said.

“I’ve had some snippets back but nothing really forms a picture and until we get through the complaints process we don’t know what we will have left to take forward.

“There is lots of stalling. It is brick wall after brick wall, and it’s taken quite a long time to go through it or challenge them and go back and chase people.”

Last year, chief veterinary officer Christine Middlemiss said the Animal and Plant Health Agency had completed its culture testing work to try and determine the source of the infection.

Ms Middlemiss said it was not possible to culture bacteria from tissue samples meaning that whole genome sequencing could not be carried out.

“This animal tested positive for bovine tuberculosis on two separate occasions using highly specific tests,” she said.

“Due to the complexity of the disease, further testing has not enabled us to use whole genome sequencing to try to understand how the animal became infected in the first place.”