I believe the original reference was in an article by Ron Thomas and Martha Schiek.

Thomas, Ronald A., and Martha J. Schiek
1988    A Late 17th-Century House Site in Gloucester City, New Jersey.  The Bulletin of the Archaeological Society of New Jersey (43):3-11.  

The article notes that 124 turned leads were found of which 69 had impressions.  Of these 61 were marked EW WILLIAM PVRVOVR 1678 other marks included W>M<168L and EW*1684*IS

Other marked leads have been found in New Jersey at Raritan Landing, the Clarke-Watson Site in Perth Amboy, and the Samuel Dunham House in Woodbridge.  

All the best,

Rich Veit
________________________________________
From: HISTORICAL ARCHAEOLOGY [[log in to unmask]] on behalf of paul courtney [[log in to unmask]]
Sent: Thursday, July 05, 2012 5:04 AM
To: [log in to unmask]
Subject: Re: Gloucester City Window lead  Ref

Sorry no- this an additional list to those in the 1986 article


On 05/07/2012 09:49, Jennifer Low wrote:
> this might be the one?
> Egan, Geoff., Susan D. Hannah and Barry Knight
> 1986 Marks on Milled Window Leads. Post-Medieval Archaeology 20; 303-309.
>
>
>
> ________________________________
>   From: paul courtney <[log in to unmask]>
> To: [log in to unmask]
> Sent: Thursday, 5 July 2012 8:41 PM
> Subject: Gloucester City Window lead  Ref
>
> Hi all
>
> Can anyone help with a reference to a marked window lead from Gloucester City, New Jersey in a paper by the late Geof Egan being prepared for publication
> The reference is Thomas et al. 1985, iv, 8-9 which I can't track down
>
>
> paul
>