LDN: New coporate image for buses; E400H

dear all,
haven't posted photos from London for some time, as relatively little happened here, and the weather was poor for photography :
The latest batch  10 of E400H tridents entered service - Metroline operate them on route 139.
Like the previous batch of 20 E400H delivered to Transdev for route 94, all the buses- except for one - do not advertise that they are hybrid buses.
Route 139 is being converted to E400H and E400 trident operation- all of them new buses.
externally the Hybrid and the diesel buses look exactly the same [except for the rear of the bus].

However, one Hybrid bus received this special extra identity; significantly, the 'roundel' has always been the traditional 'sign' of the old London Transport, and was carried on buses right to 1990.
It is modified to include 'buses', otherwise it is the same as the old roundel.will this be applied to all the buses in London? or just to hybrid buses? the clue can be seen on the publicity photos taken of the proposed new bus for London, initiated by the Mayor of London. the bus body mock up visited London, and the photos certainly show a roundel applied to the bus...Here is TEH1108 on route 139 today showing the -so far- unique livery.I also post for comparison a photo of a conventional diesel E400 on the same route.
spot the differences!
Regards