I thought it was worth making a few enquiries to the DfT under the freedom of information act. The DfT have been most helpful, but I was quite surprised at the response. I'll keep my thoughts to myself for now.
Taken from "Section 4: Use of Bus(es)" on Arriva's bid for Green bus funding:
The buses will be used on Arriva Northumbria's service 308, a frequent trunk service operating daily
to connect Blyth with Newcastle City Centre, via Whitley Bay, North Tyneside General Hospital and
Willington. The town centre area where the service originates in Blyth has been designated an Air
Quality Management Area by Northumberland County Council and Blyth Valley District Council, with
transport emissions identified as a key source of pollutants. The route also operates into the
Newcastle City Council Air Quality Management Area, which was extended beyond the city centre
to include key access routes, including that utillised by the 308. Within the city centre, the
conversion of this service would assist in reducing the concentration of emissions at Haymarket Bus
Station. The service provides important links into North Tyneside General Hospital, which would
also benefit from the reduced emissions produced by the new buses. This is a very high mileage
service [Information redacted under Section 41(1) of the Act], which maximises the benefit to
emissions levels from the use of hybrid buses. If successful, consideration will be given to
converting similar trunk services into Newcastle. The proposal has the full support of Nexus and
Northumberland County Council, both of whom have provided letters of support, which are included
within the printed packs.
I asked two additional questions. The first asking how much use the buses had seen off route (308), and the second asking whether this is abnormal from what would be expected. The responses from the DfT:
Performance data submitted to DfT shows the funded buses to have been
operating solely on route 308 from Blyth to Newcastle as specified in the bid.
The operational data provided to DfT show no abnormality in terms of the route
used by the Green Bus Fund buses.