A study can be a useful addition to a house, especially as an increasing number of people now work from home at least some of the time. However, if you only have 2 reception rooms, most buyers, especially families, expect to see them clearly defined as a separate living room and dining room, so converting a dining room into a study will not help you sell your house. Upstairs too, a small room fitted out as a bedroom is more attractive to buyers than a house with fewer bedrooms and a study.
On the other hand, a small 3rd reception room or a small box room make ideal studies, but decorating them offers a special challenge. Too often they become the private sanctuary of the men in the house – the 21st century equivalent of the garden shed – but this can make them appear cold and clinical.
Some families are very attached to their books and although there is the old saying 'books do furnish a room', in reality too many books in the living room can make this important room look untidy. The study is the obvious place to store a family's book collection. If it doubles as the family library the addition of a couple of comfy chairs and a good reading light makes it a place that buyers can see is used by everyone in the family.