During a visit to Wisley Royal Horticultural Society Garden during a pre-Christmas family get-together, we came across a wall constructed from lumps of tufa outside the alpine greenhouses. The range of calcicoles (clearly long-established) was quite impressive and I was surprised to see a few species outside of their normal range, e.g. Preissia quadrata, Tortella tortuosa and Leicolea badensis which I guess will have beenintroduced with the rock. Several of the more interesting species of these aren't shown on the NBN and Preissia appears to be unrecorded in Surrey. Whilst this is a largely introduced community, those species that are thriving would seem worthy of documenting.