Property yields in the U.K. are at record lows, and on an absolute basis real estate assets look expensive. But on a relative basis they are appealing, according to a new index compiled by fund manager AEW.

Its European Relative Value Index compares the value of real estate assets to the value of stocks, corporate bonds and REITs to determine the relative value of direct real estate. It applies a “Special Theory of Relativity” devised by AEW’s U.S. team last year.

“Whereas the trend in Europe is diminishing, [real estate in] the U.K. is becoming more attractively priced compared to 2016,” AEW said in its first quarter market overview, authored by head of research and strategy Hans Vrensen.

Looking at historical prices, AEW said U.K. real estate was expensive compared to stocks but cheap compared to bonds and REITs. Overall this made the sector good relative value. The spread between real estate yields and bonds is 330 basis points, very high on a historic basis.

That value has increased since the Brexit vote — direct property has become cheaper, while stocks and bonds have maintained their pricing.