Letter to the editor: response A letter to the editor written by John Mallard and published in the Hospital Physicists' Association Bulletin, Vol. 10, No. 3, March 1963. This letter was in response to a previous letter and discusses the number of isotope scanning machines in Great Britain. A photocopy of the letter is enclosed, as is a copy of the Bulletin this letter was published in, although the relevant pages are missing. Also enclosed is a letter of correspondence regarding the number of reprints available. 1963