We have a standard that says a given name, which is not the actual
name of the deceased, goes in brackets.
That leads to entries like "SMITH, (Mrs John)" and "JONES, (Sister
Paul)". Nicknames are a logical extension of this standard.
Lately, I've corrected a number of cases where the entry has been
something like "BROWN, (Mr W)". This is wrong on two counts: firstly,
"W" is almost certainly the initial of his given name, so it should
not be in brackets. Secondly, we don't usually index titles, so "Mr"
shouldn't be there. The correct entry is just "BROWN, W".
There is only one circumstance where "Mr" is valid - when we have an
un-named male, he can be indexed as either "BLACK, (un-named male)",
or "BLACK, (Mr)" if we wish to indicate an adult male. Either is accepted.
John