This is what Skyscraper News said about it:
"(it) will incorporate a semi-transparent image of the nearby St Stephen Walbrook Church on it mimicking a reflection".
I read that in 2008 and it stuck, probably because it conjured up an image of a Rothschild demanding a reflection of the church on the new building even though it contravened the laws of physics.
Four years later and the massed ranks of LRR were in the vicinity at the excellent The Developing City exhibition at the Walbrook Building (next to the temple of Mithras, read all about that here) in the City. Afterwards we had beer, but just before that we had an amble around the Rothschild HQ (outside of course) in search of this "false" reflection. But despite our efforts and the bemusement of security staff we failed to locate it. Is this just an urban myth or does it really exist? Help required.