Peter, at a guess I would say that she was giving a series of short blasts on her whistle to warn a yacht to clear out of the way, a fairly frequent occurrence. As you say, six shorts and a long is the General Emergency signal, maybe they accidentally pressed the button for a little too long on the last one.
As John says, Dr.Crippen was the first person to be apprehended as a result of the new fangled wireless telegraphy. He protested his innocence to the last and it seems he may have been a little unfortunate. He was a quack selling patent nostrums and the body in the cellar may have been the result of an abortion which went wrong, one of his sidelines.
The Montrose had been stripped of her superstructure and fitted with gantries. I acquired a matchbook holder some years ago engraved with the legend S.S. "Montrose", which I fondly believe to be a souvenir of same.
The Spanish Prince took her place, seen here with gantries fitted to support the anti-submarine nets strung across the Western Entrance to the other blockship Livonian on the other side.
These are a couple of rivets I was given from the Spanish Prince after the hull was removed down to the required depth. Seen sitting on a photo of her under her previous name Knight Bachelor with her bow severely damaged after hitting an iceberg.
