Remove ‘Fwd: ’ from an forwarded email subject

All works well, except that 'Fwd:' in the subject line, which I'd like to remove when forwarding

tell application "Mail"
	set theMessage to item 1 of (get selection)
	set forwardedMessage to forward theMessage without opening window
	tell forwardedMessage
		make new to recipient at end of to recipients with properties {address:"a@b.com"}
		set message signature of forwardedMessage to signature "Blank" of application "Mail"
		set stringLength to (count subject of forwardedMessage)
		set subject of forwardedMessage to (characters 0 thru stringLength) as string
		send
	end tell
end tell