Q.Holly Trees
I have a very large holly tree in the garden and recently it has started shedding a lot of leaves and looking a bit bare but there is new growth. What causes this and is there anything I can do?

You will need to investigate a bit further.
Examine the leaves, branches and trunk of the plant.
Always a good idea to remove the leaves or plant material that have dropped to help prevent the spread of any diseases.
These articles will help you pinpoint the cause which could be environmental, pests or disease.
https://www.gardeningknowhow.com/ornamental/shrubs/holly/diseases-of-holly-bushes-pests-and-diseases-damaging-holly-bushes.htm
https://www.gardeningknowhow.com/ornamental/shrubs/holly/holly-yellow-leaves.htm
https://www.gardeningknowhow.com/ornamental/shrubs/holly/holly-problems-holly-leaf-spot-or-holly-tar-spot.htm