She sent me an e-mail today (coward :) ) apologising for her reaction, explaining that I had taken her by surprise. She said it was lovely that I asked but she already had a boyfriend. Schoolboy error! I have to admit I did think about talking with her close work colleague as a preliminary. I considered ensuring through that colleague that she was actually single, but I decided against it as it smacks of schoolchildren asking friends if their friend would go out with them. I'm still glad I didn't and chose to take the action I took as I got valuable life experience from it and I'm a firm believer that you learn from your mistakes and that you get better at things the more you do them. There is bound to be some awkwardness going forward but nothing insurmountable. We were both in a meeting today for example, and we've been e-mailing each other on a professional basis too so things are already back to the way they were before.
So on the surface it's like it never even happened, but underneath there ebbs and swells a hidden secret....tide or undertow, only time will tell.