Q.Heavy leave drop
HI I have a Drimys aromatica which is in a pot I have just returned from Holiday and it is dropping a lot of leaves it is an evergreen shrub the weather has been cold and dry I have owned the shrub for years and this has never happened before it hasn’t been moved and has always looked lovely also the red stems are dull and not vibrant red as usual what can I do I DON’T want to lose the shrub

It sounds like your shrub may have had some cold damage or even lost leaves due to the soil drying out.
Prune the plant in spring and remove the damaged parts of the plant.
If the plant did soil did dry and the roots suffered; you will need to wait and see what can recover.
Water, but do not over water. This plant is also susceptible to root rot if left in soggy soil.
Good luck.