Last weekend was our work annual onsite. Colleagues from various parts of the globe came over to London to spend Saturday discussing work issues, then go to a local bar and restaurant for the evening. By the time we set off to our hotel it was 1 a.m. and I was heavily under the influence. As we went back a bird started singing. In my befuddled state I was sure it was one of the legendary Black Redstarts of Canary Wharf and was setting off to stagger round a local building site when the back of my mind dredged up the verdict "Wren".