With thanks to Richard Smiles, the latest update on the E300 situation:

27158 (SN64 OJG) – Was used from 3rd October 2014 & continues to be used on Driver Familiarisation Duties, though carries No Legal Lettering, Fleet Names or Numbers.
27160 (SN64 OJJ) – Entered Service on Friday 10th October 2014 @ 1218 on Service 36 ex Stockton to Hartlepool Marina.
27157 (SN64 OJF) – Entered Service on Friday 10th October 2014, noted on the afternoon providing a Service 14 Working from Middlesbrough Bus Station to Trimdon Avenue.
27159 (SN64 OJH) – Entered Service on Tuesday 14th October 2014.
27163 (SN64 OJM) – Entered Service on Wednesday 15th October 2014.
27161 (SN64 OJK) – Entered Service today (Thursday 16th October 2014).
27162 (SN64 OJL) – Entered Service today (Thursday 16th October 2014).
27164 (SN64 OJO) – Entered Service today (Thursday 16th October 2014).
27165 (SN64 OJP) – Was used today (Thursday 16th October 2014), on Driver Familiarisation duties, but is also fully lettered & numbered up, so also available for Passenger Service.

27166 (SN64 OJR) – Was delivered on Monday 13th October 2014, with Branding applied by/at ADL prior to delivery to Stockton – Orange based Graphics The Zone/Time Zone Version.
27167 (SN64 OJS) – Was delivered on Tuesday 14th October 2014, with Branding applied by/at ADL prior to delivery to Stockton – Orange based Graphics The Zone/Time Zone Version.
27168 (SN64 OJT) – Was delivered on Wednesday 15th October 2014, with Branding applied by/at ADL prior to delivery to Stockton – Orange based Graphics The Zone/Time Zone Version.