For whatever it's worth,
BLND at 330 pence, dividend yield 6.93%... [minus possibly credited REIT withholding tax]
LAND at 493 pence, dividend yield 8.15%... [minus possibly credited REIT withholding tax]

At the moment,
BLND at 390.4 pence, up 18%
LAND at 633 pence, up 48%

I presume this is mostly a short term move and prices may dip again, but it's a nice start.
Indicated forward yields currently 5.77% and 6.41% before 20% REIT withholding tax.

Again, dividend driven investing is almost always a bad idea, but as these are REITs forced to have high payout ratios (90% of property rental profits before any realized gains), the dividend yield correlates closely with the theoretical earnings yield, so it's not an entirely useless crude guide to valuation levels. Whether they are sustainable or not of course requires understanding the underlying businesses, but if things continue as they are (a big if), implied valuation levels are not hard to estimate.

The secret to happiness in investing is to look at the prices of your holdings frequently only when they're rising : )

Jim