3.1% rental yield for central London real estate?

The Trust has £1.15bn in CBRE valued assets, yielding 3.1% gross rent income, £290m of debt that costs 2.1%. If debt costs went to about 6.5% then there would be no distributable income and the equity would be toast.

The managers of the fund are paid on AuM so are benefited by as low a valuation yield as possible.

Investors want out of this Trust, with one blaming Brexit for making the UK 'particularly risky' etc.

That just shows how wrong headed most of these people are. They have held on to what are now vastly over-valued generic assets. 

The truth is Brexit should be good for the UK but London is uneconomic and the medium term outlook for real rents is poor, so the valuation of these assets should fall a lot over the next few years. A BoE rake hiking cycle will also reset valuations and funding costs.
https://www.bloomberg.com/news/articles/2018-11-06/brexit-fears-said-to-imperil-1-1-billion-london-property-fund?srnd=premium-europe