It depends what you mean by "directly operated". It doesn't dump the brake pipe, but it does (presumably overrideable by the driver e.g. in case you're on fire in a tunnel) put the brakes on without a chat first, same as the red handle on say Class 15x stock.
It's normal European practice to have it split in this way, it may even be a UIC standard. Certainly all German stock does.
It does make a fair bit of sense - use the red for something wrong with the train that needs it to stop now, e.g. a derailment, tree through the window, fire or something, use the green if, say, a passenger is assaulting other passengers, as there's not a lot to be gained by stopping the train at all in such a case, it's better to call BTP to meet the train at a station (possibly not even the next one).