SIR By what authority, I wonder, does Linda Parker (T&A, May 12) offer the contents of her letter as fact?

I do not like the thought of carrying out trials on animals but we have to face it, experts in the field say there is no alternative and I will continue to believe them.

Obviously there can be no anonymity in my case and I should not seek any, nor am I ashamed.

Philip Bird, Nab Wood Terrace, Shipley