EXHIBIT 99.1
JOINT FILING AGREEMENT
The undersigned hereby agree that the Statement on Schedule 13D filed herewith
(and any amendments thereto), relating to the Common Stock, no par value, of
Duquesne Light Holdings, Inc., is being filed jointly with the Securities and
Exchange Commission pursuant to Rule 13d-1(k)(1) under the Securities Exchange
Act of 1934, as amended, on behalf of each such person.
Dated: July 17, 2006
DUET INVESTMENT HOLDINGS LIMITED
By: /s/ Xxxxx X. Xxxxx
--------------------------
Name: Xxxxx X. Xxxxx
Title: Chief Financial Officer
DIVERSIFIED UTILITY AND ENERGY TRUST NO. 1 (DUET1)
By: /s/ Xxxxx X. Xxxxx
--------------------------
Name: Xxxxx X. Xxxxx
Title: Chief Financial Officer
DIVERSIFIED UTILITY AND ENERGY TRUST NO. 2 (DUET2)
By: /s/ Xxxxx X. Xxxxx
--------------------------
Name: Xxxxx X. Xxxxx
Title: Chief Financial Officer
AMPCI MACQUARIE INFRASTRUCTURE MANAGEMENT
NO 1 LIMITED (RE1)
By: /s/ Xxxxx X. Xxxxx
--------------------------
Name: Xxxxx X. Xxxxx
Title: Chief Financial Officer
AMPCI MACQUARIE INFRASTRUCTURE MANAGEMENT
NO 2 LIMITED (RE2)
By: /s/ Xxxxx X. Xxxxx
--------------------------
Name: Xxxxx X. Xxxxx
Title: Chief Financial Officer
