The following extract frown the _Handbook of English Ecclesiology_, p.
190., may be of some assistance to your correspondent:
"YEW. These were planted generally to the south of the church, to
supply green for the decoration of churches at the great festivals;
this tree being an emblem of immortality. It is a heathen prejudice
which regards it as mournful. It is not probable yews were used as
palms; the traditional name given to the withy showing that this was
used in the procession on that festival."