German title of 'Old Mother Riley' (4)

I believe the answer is:

herr

'german title' is the definition.
(I've seen this before)

'of old mother riley' is the wordplay.
'of' says the answer is hidden in the clue.
'HERR' is hidden in the letters of 'old mother riley'.

(Other definitions for herr that I've seen before include "German man's title" , "European guy" , "Form of address for German male" , "German form like Mr." , "A German gentleman" .)

I've seen this clue in the Evening Standard.

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