Just a Coincidence?

The bus explosion also happened to occur right in front of the headquarters of two Israeli-based security firms, Fortress GB and ICTS UK Ltd, both based in Tavistock House, and having Underground-line security contracts.

Just a conspiracy coincidence, surely. The other explanation that comes to my mind is more along the lines of the "horse head in the bed", a warning send to these Israeli firms. But who send this warning, and what for?
July 7th Truth Campaign - The People's Investigation into 7/7