Sussex-based screenwriter Carla Lane is sending her OBE back to the Prime Minister in an animal rights protest.
The comedy writer is handing the honour to Tony Blair after she found out the former Huntingdon Life Sciences Managing Director Brian Cass was made a CBE.
Ms Lane, 65, who is a veteran animal rights campaigner and runs a sanctuary in Horsted Keynes, won an OBE for penning comedy greats including Butterflies and Bread.
She was furious when she realised Mr Cass had been honoured for his work in the pharmaceutical industry.
She said: "When I discovered someone who mutilates animals had been given a medal, I thought, 'This is the bitter end, what can I do?'
"I decided to send my OBE back. I no longer want to be part of that group of people in this country who have medals.
"My OBE doesn't mean anything to me. If they can give him an honour like that, I don't want to know."
Ms Lane says she cannot believe Tony Blair is supporting Mr Cass's controversial work at the centre, which carries out tests on live animals.
She found out about his award when she read an animal welfare magazine.
She said: "I have done everything I can to get Tony Blair to listen to people. I'm appalled.
"The animal welfare people of this country are so frustrated, as we don't have a voice. It's absolutely disgusting.
"It was such an honour to receive the OBE for my artistic contribution in TV in 1995. I treasured it.
"Now I cannot bear to open the box after I found out Mr Cass received a CBE in June. It is going back to Tony Blair on tomorrow. I feel let down by this government as they are just totally disregarding animal cruelty.
"Although Mr Cass has left the company, Huntingdon still goes on. If they could give me a comprehensive list of what good is being done there, I would be very glad to receive it. But they can't."
Ms Lane has spent 42 years fighting for better animal welfare and has been at the forefront of a Stop Huntingdon Animal Cruelty campaign.
Last year, Mr Cass was treated in hospital after an attack outside his home. He left Huntingdon soon after to work in the US.
Downing Street justified the decision to honour Mr Cass on the grounds that Huntingdon Life Sciences "is an extremely successful company that carries out important work in the face of sustained intimidation".
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