London's hidden museums and libraries

A 25-foot Alaskan totem pole outside the main entrance gives a clue as to what’s in here: a wealth of quirky anthropological and natural history treasures. You can while away hours perusing the place, but the Grade II-listed natural history gallery – refreshingly devoid of computer touchscreens – possibly contains the most memorable: a comically overstuffed walrus (the work of an over-zealous 1880s taxidermist).

The world’s only museum dedicated to fans. It’s a tiny space consisting of two rooms with an overall collection of 3,500 antique fans, some of which date as far back as the eleventh century. If you’re not a fan fan, head for the Orangery where teas are served at 3pm on Tuesdays and Sundays.

The gallery’s quite extraordinary, lined with botanical paintings made in the field all over the world during the nineteenth century by the remarkably intrepid Marianne North. The gallery walls are lined with more than 800 paintings of flowers, landscapes, animals and birds made in America, Canada, Jamaica, Brazil, Tenerife, Japan, Singapore, Sarawak, Java, Sri Lanka, India, Australia, New Zealand, South Africa, the Seychelles and Chile.

The world’s oldest establishment dedicated to collecting information about the Holocaust is currently fundraising for a move to a larger building that will allow it to show larger, more regular exhibitions. Try to help.