Sergeant Liam Hogan states ... "I took an additional statement from Mr Smith as requested. His wife does not want to make another statement".
http://www.mccannpjfiles.co.uk/PJ/MARTIN_SMITH.htm
Suggesting that Mary Smith, the only one of the family to address the man did make a statement. Which must have been recorded by the Guards since she did not return with the others to make one for the PJ.
I think of this as Mr Smith said to the police that his wife had stated to Mr Smith that she did not wish to make a further statement.
I do not wish to attempt to criticise Sergeant Liam Hogan. I simply cannot see whether he was in a position to know much about who had given previous statements, about what, or when.
Martin appears to be of the opinion his wife did not wish to add to a previous statement. There is nothing in the files, beyond Martin's statement, to indicate a previous statement.
I do not have a comprehensive knowledge of media reports from the time. I had no interest in the case. There may be something in those to suggest an earlier statement by Mary. I can find nothing to persuade me Mary made an earlier statement, and I have no reason to impugn Martin Smith.