Can somebody please tell me the IBU for this recipe? I have seen 40 and 48 on these forums and I am unable to find a copy of Marc Ollossons book to buy

There are many many threads which mention this recipe but the actual IBU or grist amounts seems to vary.
I am assuming it is:
Pale malt: 96.2%
wheat malt: 3.8%
IBU: 40 using appropriate quanitity of cascade hops.
Is this right?
Thanks.