I was up there again over the weekend with another Navigation course. However the rain was being whipped off the top so we didn't climb it and moved swiftly on. I''ve done a bit of digging for you and found this on IWB
The initials are of Isaac Watt Boulton,
Born in 1823 (died 1899)in Stockport I.W.B.became an eminent Industrialist in Ashton under Lyne,building amongst other things locomotives, he was also a J.P. and an Alderman,as well as being a keen " rambler" he was an authority on The Peak District, and campaigner for public access to ancient paths over Kinder Scout.
on 20/5/1893 The Aston under Lyne Herald published an article from I.W.B.describing a walk done the previous weekend "that may help some of your younger readers who believe in walking as a healthy exercise & are anxiously looking forward to the Whitsuntide weekend for the purpose of going on a long tramp over mountains and moorland."
I.W.B.travelled by train to Woodhead arriving at 0800 and breakfasted on "oatcakes off the flake,fresh butter and a glass of beer" whilst chatting with " the genial landlady" of The Millers Arms at Saltersbrook - now long gone.Opposite the ruins against the wall can be seen an inscribed stone -I.W.B. -Gordon Danks, Area Ranger remembers replacing it there a few years ago.

when we reach Lady Cross there are various initials carved on it - I.W.B. as well as a cross,plus N.B. and M.B - having researched I.W.B.on the internet ( Google search) I wonder if M.B could be Matthew Boulton his relative.
Heading across towards Shepherds Meeting Stones we pass a tapered rock near Dean Head Stones at Grid Ref.SK 1382298553 marked I.W.B. and H.P.B.
Close to here on the smaller of the stones at Hoar Stones Grid Ref. SK1557298245 can be seen a X and the initials W.P.M.