On Mon, 9 Oct 2017 20:01:00 +0100, Basil Jet wrote:
I haven't had a good look, but I think they have completely demolished
the surface building that's been there as long as I remember, and are
building a new block, probably of flats. I imagine its function as an
emergency exit has not been compromised, although I'm not certain.

It seems it isn't going to be flats:

Application Number: P2015/1008/FUL

Address: Ventilation Shaft Adjacent to Kestrel House, 191 Central Street &
Land near City Road Bridge, City Road, London EC1

Description: Part demolition of the existing building and construction of
a new energy centre comprising a part three/part four storey extension
including heat exchanger coil, 4 storey stack of containerised plant to
the corner of Moreland and Central Street, new thermal store and flue on
eastern elevation of Kestral House. The new buidling will be metal clad;
new vehicle access off Moreland Street, raised planter beds and boundary
walls. (Reconsultation following revised design and details to the main
finished design and external appearance of the proposed energy centre)

More via the search form at
http://planning.islington.gov.uk/nor...ralsearch.aspx
and also P2017/0764/S73 (variation of conditions) and various others
for details such as piling method etc.

LUL service stairs are on the plans as is a Heat Exchange Coil above
the vent shaft so it appears the Northern line will be contributing to
the heating of Kestrel House.

http://planning.islington.gov.uk/Nor...s/00434738.pdf for
the proposed site plan.