Urgh this could get messy.
Our road is a sort of oval, so some of the houses don’t sit on rectangular plots. This includes ours, which is sort of trapezoidal, with the short end at the front of the house widening out to about twice as wide at the end of the garden. Same goes for our next door neighbours where we both have awkward unusable triangular driveways. Basically the architect’s idea was to extend in parallel with the boundary, rather than parallel to the existing house wall, and also make part of the back face of the extension face at an angle into the garden, creating a semi-courtyard type of effect whilst also cleverly facing that part of the extension more towards the south.
A really simple idea, but opens up lots of possibilities for how we use the extension space, whilst also using our dead space in a clean organised way that would look natural from the garden and the road. Also good for privacy with the neighbours (both ways). Weird how a non-architect brain finds it hard to think of rooms in anything other than rectangle shapes, no matter how hard you think about it.