Excessive Boat Race security?

I was at the Boat Race yesterday and was staggered to see two boats crammed with what appeared to be Special Branch officers following the main race as well as a police boat. Was it really necessary? Or was it to cement the feeling of a threat? I can't really see what they'd hope to do even if someone did launch something questionable at either boat! Given the apparent lack of security at many Oxbridge colleges I suspect there are probably easier and more high-profile Oxbridge targets.

That said, something must have happened to make that Cambridge boat take on so much water. Oxford do have experience of protesting too....