RAIN INGRESS WHERE TOP OF WINDOW FRAME MEETS MASONRY

[Mae West]

During a sudden exceptionally heavy and, luckily short, rainstorm this morning, water came pouring in at the top of my window frame from where the frame meets the masonry.
Outside, the wall is covered with that thick render material which looks like tapioca. (Sorry I don't know the name of this stuff). Because of this, there is no way for me to actually climb up and view the window frame where it meets the brick of the wall.
Very considerable water came in across the whole of the upper frame.
The window itself is at least 20 years old (I've only been here for two years so am guessing). It has locks so ancient that they can't be replaced and the previous owner left no keys. I've actually had some keys created by a locksmith. All the double glazing is in perfect condition, with no clouding or damp damage so I'm very reluctant to have to replace the entire window as it's a large, wide kitchen one.
Would be very grateful for advice so that when I get contractors to look, I will know if they're telling me a story or not. Also, being female, I find some contractors try to mess me about.
My brother seems to imagine I can 'paint' some kind of sealant onto it but I really don't think that would suffice and, in any event, there's this thick render stuff on top of the brick so how do I even reach the window frame/brick myself? My tallest ladder doesn't get me high enough.
I need the cheapest but most solid solution possible and I don't think I'm going to be able to do this job myself.
Unfortunately my camera does not show the water ingress well but you can see how much has collected on the sill. The window itself appears to be made of metal - aluminium I guess.
Thank you for reading.

 

[Wayners]

I've cured a few widows that leaked by injecting foam around frame then new mastic around to seal.
Think the lack of cavity tray (look them up) in properties is not helping many with similar problems but not saying that's your problem.

Re window handles. They are under £5 and available at all diy stores so can't you get them swapped as only 2 screws and 2 min job, they come with keys. That's unless you have something more specific. No picture of those

 

[Mae West]

Thanks. I know what you're saying. I can change locks and handles myself. Did it at the last house but these are so old fashioned that the fixing of the entire mechanism is like a different thing altogether. Not like the modern ones which are totally easy to deal with. You can't buy this kind any more. I've spoken to manufacturers and had several people check my findings. Basically stuck with these old things unless I replace all my windows.

As to the window leak, that sounds like a sensible idea. I will bear that in mind when I can get a contractor to look. It helps when I can say 'What about?' because even if it's not suitable, it makes me sound as though I'm not a total pushover.

 

[Wayners]

Mother in law had similar problem and all the fitters wanted to put new window in so I ended up getting ladder, masking window frame to cover and covering window below (as bedroom window leak) getting foam gun and pushing a mastic nozzle on the end and ramming it in the edges ever few inches and firing a blast of foam.
Had tea and biscuits. Cut foam back and removed masking. New white mastic around window and been a few years now with no trouble

 

[Mae West]

Great. The tea and biscuits sound good. I'm going to look into that.
Thanks very much for the advice.