Gingernuts, I think you are wrong on a number of points:

If the nursery ceases operation the entire house reverts to a single dwellinghouse (one of the planning conditions). Any further change would need to go to a planning committee, even a doctor's surgery would require planning permission.

Of course not, but then I don't think there are any restrictions on external lighting on residential properties. There are possibly more restrictions on external illumination for business purposes, so you are probably best off with a nursery which has no external signs of use as a nursery.

Again no basis in reality, but you might be aware that other properties in Liphook have been altered to allow easier access for the disabled residents. I don't think this is something you would really want to legislate against, nor is there anything about it in the covenant.

would also require a new planning application. Due to the restrictions placed on the owners by the existing permissions.

This house is still their home as well as being a nursery. Both a childminder and a nursery would constitute a business and could be closed down by the same restrictive covenant. Other businesses on the estate may well find themselves falling foul of the same covenant that fails to distinguish between any type of business, other than doctors and solicitors. I believe these professions were singled out not because of the traffic generated (although noise may be a consideration) but because they were nice middle-class professions.

I am also pleased that TLERA finally explained to their members what their position was, but I was disappointed to read some of the points they made, some of which I did not feel were fair or truthful (i.e. if you allow this then Sainsbury's will be allowed to build on the Triangle).