Exhibit 23.1



CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the  incorporation  by reference  in  Registration  Statement  No.
333-40472 of KeySpan  Corporation on Form S-8 of our report dated June 29, 2005,
appearing in this Annual  Report on Form 11-K of the KeySpan  Energy 401(k) Plan
for Management Employees for the year ended December 31, 2004.

/s/ Deloitte & Touche LLP
- -------------------------
New York, New York


June 29, 2005