At dusk on 26th February 2014, I heard a juvenile Tawny Owl Strix aluco calling in the gardens of Buckingham Palace, Greater London. Typically, young Tawny Owls in London, such as the birds that are regularly observed at Kensington Gardens, are not seen until late April (Des McKenzie pers. comm.), so this observation was very early. I was not able to see the chicks at Buckingham Palace on 26th February so could not determine how old they were. I returned before dawn on 5th March and located two large juveniles, estimated to be around 40 days old. From this estimate, the birds had hatched around 24th January and the eggs, based on a minimum incubation period of 27 days (Ferguson-Lees et al. 2011), would have been laid in late December 2013. This, as far as I am aware, was the earliest documented breeding of Tawny Owls in Britain at the time.