Sat pictures are meaningless - they do not show the borders. Google Earth only show the border to the end of the river, beyond that it is in dispute.
The British map for dummies is worthless as the line drawn on it does not exist on any official map - otherwise they would have shown it.
That area is in dispute and therefore no one can say whether it is Iranian or Iraqi waters.
Strangely, the boat thet boarded had been anchored there for three weeks before the boarding and is still anchored there.
Also the first Iraqi comment issued by the head of the coastal area in Basra said that the fishermen had told them that the British were operating in Iranian waters. Fishermen who are out there every day know the area.
Finally, they could not even get the UN to go along with the fiction of being in Iraqi waters, which could easily be proved if they had a internationally recognised border in that area -- they do not, so that was struck from the complaint.
Stay away from disputed waters.
I think the Royal Navy GPS system and Internationally recognised maritime charts are slightly more accurate than the opinion of uneducated fishermen. But I could be wrong.....