Art in Official Publications

I was recently checking the official publications request slips for April and noticed without a doubt that April was definitely the month of the art book; whether it was about Degas, Lady Butler (battle artist), origins of chintz or even costumes in Scottish portraits.
I am used to and expect to see readers consulting publications on parliamentary papers, journals of the House of Commons/Lords, United Nations publications etc. but April was very much to do with art.
The Official Publications collection has a wealth of art books as the National Galleries and Museums are under the remit of the official publications collection as they tend to be funded by Central Government.