One of the advantages of buying a shared ownership lease is that you, the leaseholder, will have a friendly and professional social landlord/housing association to deal with rather than the pot luck of a private sector freeholder. However, for some leaseholders things are not as clear as they might be.
In particular, what happens if the structural parts of the building, for example the roof, need repair? Many shared ownership flats are in developments where the housing association does not own the building. That might be, for example, because the housing association only has a few of the flats, and the rest is owned by a private sector freeholder. In that case the housing association itself is a leaseholder. So who is responsible for repairing the roof in the example set out above? The answer is that the freeholder is, not the housing association. You might expect the shared ownership lease to impose some obligation on the housing association, so that in turn they can use their head lease with the freeholder to ensure the roof is fixed. But some shared ownership leases do not impose any direct obligation on the housing association at all. The only obligations on the housing association are indirect, for example to jointly insure, or to pursue the freeholder only if the shared ownership leaseholder indemnifies the housing association (potentially expensive).
The result is that a shared ownership leaseholder might find themselves without any direct remedy under their shared ownership lease to ensure the roof is fixed. Of course they may have some other legal rights against the freeholder, for example to sue in negligence or nuisance, but these rights are far trickier to enforce. Shared ownership leaseholders can find themselves having to deal with a remote and unresponsive freeholder rather than their social landlord. Of course something can be done, and that is where specialist legal advice comes in. However, this is one of a number of examples where being a shared ownership leaseholder is not what it is cracked up to be.