Wet window reveal

[Liamm_n]

I've had a quick browse through similar topics so I think I may already know what I have to do, but I need confirmation/reassurance before I do it.
A few months ago we had our kitchen plastered. I stripped all the walls and when it came to the reveal we had a plastic trim around the frame, I pulled it off and that revealed a ~2inch gap from frame to wall.
Now when it was plastered the guy has done it all the way upto the frame.
Since then any bad weather this has happened, starting from the top/corners of the frame eventually going down

The weather these last few weeks has been atrocious, it's been gale force winds and heavy rain all night so this is this morning.


Am I right in thinking the gap that has been bridged is the reason for this? And I'll now need to cut the plaster back again and put a trim on?
I saw a post from 2016 which suggests just that:



Any help much appreciated!

 

[JohnD]

Photos of the outside please

Will give clues on how the rain is getting in.

 

[Liamm_n]

What I have just noticed is this.

The frames were resealed last year and the opening window adjusted because there was a draught coming through. We had no problems since then. This only started just after it was plastered, the first sign of rain since it dried out and it ended up similar to how it is now. The back of the house does take a battering when weathers bad