The HMS Roberts lost control and steamed in a circle mid-pond while the Westfalen and Suffren try to keep the Warspite from engaging the Maru. As the action passes the Roberts she apparently leaks just a touch too much and goes under. Apologies for the watermark mid-screen.
When i first saw the sink I didnt have a good viewing angle of the effect the Warspite's wake had on the Roberts, but after watching the video I'd agree. Her decks arent bolted down for this sortie and it looks like the wake caught her kind of sideways.