I have a very mossy lawn, which I gather needs (amongst other things) a
good working over with a fork to provide better drainage. I have
acquired a gadget which purports to perform this rather onerous task
with minimal effort - think it came from the mailorder firm Coopers or
somewhere?

It has two 6" wheels and a long handle, with lots of spikes on springs
attached to a 15"-wide frame which spans the wheels; the spikes prod the
ground to a depth of approx 2" as you roll this contraption along the
lawn. (It looks a bit like one of those old-fashioned manually-powered
cylinder mowers with no grass box.

Is this spiking deep enough to do any good, or are we talking chocolate
teapots here?

Thanks
David