By Charlotte McIntyre Sian Welby announced live on Tuesday’s Captital Breakfast that she is going to be a mum. Sian Welby shared the exciting news live this morning with her Capital Breakfast co-hosts Roman Kemp and Chris Stark and with Capital listeners revealing that she is thrilled to be expecting a baby later this summer with her radio producer fiancé Jake Beckett. Sian Welby said: “I’ve got a bit of an announcement for you! I’m pregnant! I don’t know how I’ve managed to keep it from you for so long. The lies, the deceit, the mocktails! I couldn’t wait to tell you. This is a whole new jour…