Peter Noone wrote:
After having an extension built three years ago my enclosed back
garden was turfed and everything seemed perfect until about a year
ago when the grass became very patchy and seemed to recede to be
replaced by large areas of clay. It's even more galling that prior
to the turfing the lawn had always been fine.

The open plan west facing front lawn was also done slightly later
but
is not suffering the same conditions.

Can anyone please suggest simple straightforward steps to return
the
lawn to the grassy area it once was that my children can play on. A
local small bedding plant seller has suggested Canadian Grass Seed
&
sprinkling top soil on it but the national chain round here doesn't
stock it the grass seed and has not proved to be very helpful.

Any suggestions please would be kindly received

I don't know how soon after the turfing you started getting the bare
patches; but if the turf went on top of the old lawn it may have died
because it didn't have properly prepared soil to root into. I suggest
scratching up the bare patches to see what's underneath: if you find
a serious layer of dead plant matter, tell the turfing contractor to
come round and do it properly this time, or at least go round and
smash his windows.

Otherwise, the clay you mention suggests the soil may be difficult to
keep moist in dry weather. You could fork and rake in some organic
material and sow some more seed, and nurture the result rather
carefully for a year or so. For a play lawn, the cheapest seed is
usually the best, as it's likely to contain the tougher grasses.
Don't listen to anybody trying to flog the Canadian stuff: it's a
great country, but this isn't Canada.

--
Mike.