I suppose if the question asked was about readers' "best loved author" there would be little doubt, but the word "greatest" holds so many elevated and broad-ranging implications.
The writer with the greatest influence? Arguably so.
The greatest technician? As opposed to Rushdie or McEwan or Byatt or Ishiguro? Well...
At any rate, for my money the real surprises lie in the other rankings. Terry Pratchett is second. Nothing wrong with this, of course, but it makes me wonder about the age of the respondents.
But Nick Hornby, for God's sake, is at #8 between Pinter and Byatt. Rose Tremain doesn't rate a mention. And the list is almost entirely English novelists (apart from the Poet Laureate and a smattering of playwrights and a couple of token Scots). Cast your eye down the list. Fascinating.
My picks from this selection?
Novelists in no particular order:
Ian McEwan (sometimes)
Salman Rushdie (most of the time)
Diana Wynne Jones
Peter Ackroyd was the only biographer/history writer listed - no mention of:
John Julius Norwich
It's years since I've read Lessing or seen a Stoppard play but I feel they ought to get a run in the A team. The young crowd (all those Smiths, for example) can wait their turn.