I happened to be in a cycling shop and overheard a Sales Assistant tell a customer to get down to Covent Garden (He couldn't remember the store's name) and buy a merino wool base layer if he wanted to stay warm in the extreme cold snap we recently had. Two days later I happened to be in Covent Garden and stumbled across the very same top. I bought 2, they fitted like a glove. I went for a long bike ride that evening in sub-zero temperatures and despite sweating profusely I stayed warm and dry. This top also works well as a single layer under a soft-shell wind-stopper.
I went back the next day to buy two more, unfortunately there was only one left in my size but I'm still looking.