To be more correct Peel are seeking investors in Peel Airports (i.e. not just DSA).
This has been underway for some months and acknowledged publicly by Peel. In fact I think there were press releases posted on DSA, DTV and LPL web-sites.
Certainly on LPL web-site in MAY, see:
Media Centre*|*Press Releases*|*Peel Airports considers partners at Liverpool John Lennon Airport