Brrrr...

[Gazman16]

Any grease will do, Vaseline is just handy to carry and it you use it on things like door multi point locks as it is clear it doesn't reck clothes like dark colored grease can if you catch yourself on the edge of the door.

Good pic of the hinge, That is a friction hinge.
Can you post pics of:
The lock keeps on the frame
And the locking gear on the edge of the window?

They maybe adjustable to increase compression

 

[Roger465]

Can you post pics of:
The lock keeps on the frame
And the locking gear on the edge of the window?

Ummm... don't think there is any fancy locking gear, unfortunately... just this:

 

[cwhaley]

+1 to @Gazman16 's suggestion of blocking up the trickle vents.

I blocked all mine with insulating expanding foam (don't go wappy with it) and the reduction in external noise entering the house was very noticeable. It also meant the constant stream of cold air entering the room and dropping down all but stopped.

We open the windows at certain periods of the day for controlled ventilation.

 

[Roger465]

We open the windows at certain periods of the day for controlled ventilation.

You wouldn't if you lived in N Ireland

Seriously though, I'll stick some tape over it for now, just to see if it makes a difference...

 

[Roger465]

Here’s another thing… the main mahogany frames seem to still be in good nick after 25 years, but a lot of the little battens that trim them round the edges of the glass panels are getting tattered. Sorry, don’t know if they’re mahogany too or not, and it’s cold and dark and wet…

Is it maybe standard practice to replace them after this length of time? Can you buy strips of the right kind of mahogany batten to do it etc?

Thanks