THE office building at 183 Madison Ave. and the office condos at 100 Fifth Ave. are now part of Rock Investment parent company’s UK insolvency proceedings.

The company, headed by colorful Paul Kemsley, bought 183 Madison for $107.5 million in June 2007, and paid $152 million for 100 Fifth Ave. in February 2008.

Kemsley was most recently appearing in the UK’s version of “The Apprentice.”

As shareholders, PricewaterhouseCoopers has taken over operations as the administrator of some 47 properties, most of which are in England.

But salivating investors hoping for a fire sale won’t be getting any fast liquidations.

“Our strategy so far is to retain, work and enhance the value of these assets through a program of fully funded capital expenditure,” e-mailed Barry Gilbertson, specialist real estate partner with PwC’s London office. “As administrators, we have no current intention to sell the assets. . . We are following a hold strategy, not a sell strategy.”

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Jaws dropped yesterday morning when Cushman & Wakefield honcho Joe Harbert noted that net effective office rents are down 44 percent.

“The decline has been steeper and quicker than the last recession,” said Harbert about the citywide rent slide.

Over the last quarter, Class A Plaza District rents, which had been tiptoeing into the $200s a square foot a year ago, are now averaging $84.07 a foot. But with even more pressure coming from sublease availabilities, those prices are falling to $65.59 a foot.

Yet there has been no “flood” of sublease spaces, and Harbert said several blocks have been taken back by companies that realized the end wasn’t near.

Still, there is 41.2 million feet available — as much as Philadelphia’s entire central business district.

One good piece of news for SL Green Realty, the real estate investment trust that owns but may sell 485 Lexington Ave., came from C&W’s leasing ace Tara Stacom, who said Citigroup is pulling its space there from the sublease market while it assesses its needs. Citi originally had 250,000 feet up for rent.

On other fronts, the trend of “extend and blend,” or extending leases while dropping rents, is continuing for early renewers.

Renewals and bargain hunters with more settled businesses also sent leasing activity up to 1.4 million feet in June — well over May’s snail’s pace of 500,000 feet.

Brokers report more deals are being “converted to paper” and should sign over the summer.

But with leasing at a mere 6.4 million feet since January, we’re still on track to be the worst year since 2001, when only 11.5 million feet were leased.

While the large investment sales market is off by 80 percent due to lack of both financing and product, some lenders are “extending and pretending” by pushing out loan expirations under the old subprime mortgage theory that “a rolling loan gathers no loss.”

Maybe Congress will figure that one out.

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You knew it was a jungle out there but now there’s proof.

German-born local artist Sandra Spannan has just transformed a brick gate way in Midtown into a welcoming, plant- themed mural, ap propriately titled “Jungles of Man hattan.”

As we noted back in January, the then graffiti- covered Artkraft Strauss building by the West Side Highway and West 57th Street had turned into a dilapidated eyesore.

Sure, the hodgepodge of graffiti was created by street artists from around the world before nuisance local taggers chimed in.

And sure, the environmentally conscious Durst family, which owns the building and allows daughter Anita’s arts group Chasama to use it for studios and rehearsal space, kinda liked it that way.

But when we finally got embarrassed for New York and complained, Durst’s flack promised the building would be refurbished.

They’ve now come through with something that made us smile.

In a statement, Spannan said the mural “reflects the emerging trend of growing trees and expanding parks near the waterfront while representing our local art community.”

Now, if they could just fix those broken windows. . .

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