Planning permission on PILs garden

[CalamityJ]

My PILs own an end terrace with a large garden. They are getting very infirm and the decision has been made that we need to live with them.

One solution is to build a house in their back garden. They own the end house plus the garden behind plus the extra irregular green coloured shape garden. It's all one big garden really! It's a dead nice area so we'd jump at the chance for the kids to live there! Whereabouts do you think on the garden would we be allowed to put a house? The other big green shape is now extra bits of their neighbour's gardens individually. Thanks.

Which is their property? Are you planning a big house for all of you, or just to build a house for yourselves next to their house?

Is there an access to the land other than via their property? Any precedents or restrictions locally?

I don't really understand the diagram. Are the smallest rectangles all houses?

What was the green land originally? Has it always been part of the garden, and if not does it have PP to be used as such?
Also how is it accessed?

It would be cheaper for you to move in to the family house and build a one bed annex in the garden for the parents. Is your husband their only heir?

I can't understand the diagram either. Are the little rectangles parking spaces or something?

Are the small rectangles garages? Parking spaces?

Rectangles will be garages.

Theirs is the larger rectangle at the bottom of the green shape. The little rectangles are garages. They have the first garage which could be knocked down for access. They got change of use for the green shape to be garden not agricultural land over 14 years ago before I met DH.

They have separate bedrooms and a room for the cat Their care issues are not mobility related. Yes DH is an only child.

Two separate houses. I love them but not much

I think you will need to use a planning consultant. Change of use and access issues are complicated. It looks like the access to the new property will be via the garage area which is likely to be privately owned. Looks like a good size piece of land .

They own the garage area too but not the garages individually except 1. This might be the worst drawing on a diagram on MN attached!! They own everything within the purple area.

"I think you will need to use a planning consultant."

This.

I am one, if you wish to message me (I run a combined Planning Consultancy and Architectural practice).

You need to be looking at the stuff @Seeline has suggested, plus the wider context of the site (does the land lie within defined settlement boundaries? Is the settlement considered sustainable?), among other things.

Gardens used to be considered 'brownfield' (previously developed) land, which was much easier to get Planning Permission for, but policy has changed on this. Planning Authorities also tend to be against what they call 'backland' development (building behind a line of existing houses), so don't expect it to be straightforward or easy.

I love the diagram! Looks like a sizeable chunk of land. You need a local professional to take you through the process. Have you identified an architect yet as a good practice will have all the connections you need.

Thanks for the advice and the kind words about the dreadful diagram

@Sensus if I can contact you that would be so helpful. Backland development isn't a phrase I've heard before.

@CalamityJ you have a message, I hope!

Thank you I've emailed you