A date with “Iris”, Sep 2022

A date with “Iris”, Saturday September 10th 2022

The Great Central’s DMU Gala offered the rare chance to rake in M79900 (formerly DB 975010) for a few miles plus the GCR’s green and blue 3 car 101 Met Camm’s. “Iris” looked and sounded the part working singly, dragging a CCT van, and in multi with the green 101 set. A very enjoyable date it was too!

With the green 101 alongside, “Iris” hauling a CCT arrives at Quorn with the 0955 Leicester – Loughborough on September 10th 2022

“Iris” passes the impressive Rothley semaphores with a service from Loughborough on September 10th 2022

With her exhaust pipes making Iris looking more bubble like, Iris arrives at Rothley on September 10th 2022

Banbury bound as she would have done from Bletchley back in the early 60s, Iris looks good leaving Loughborough for Rothley on September 10th 2022

History – Derby lightweight, M79900 “Iris”

This single car railcar was built in 1956 at Derby Works. The Derby Lightweight railcars were designed by R A Riddles with his team of engineers ushering in a new age of fast trains for the travelling public whilst greatly reducing costs compared with steam traction.

They entered service in 1954 alongside Metro-Cammell lightweight railcars both having an early “yellow diamond” multiple control system. They were the forerunners of a host of diesel railcar designs that operated for over 50 years.  

79900 and 79901 were built in 1956 uniquely as single cars as a cost reduction experiment for the Banbury, Brackley and Buckingham branch. Following their introduction passenger numbers greatly increased but not enough to cover all costs. This line closed in December 1960 and M79900 and M79901 were transferred to the Buckingham to Bletchley service, again replacing steam traction. December 1966 also saw this line close as part of the extensive Beeching cuts.

With no suitable branch line work M79900 became a departmental vehicle being renumbered RDB 975010, initially used for route learning and later for research (based at Derby RTC, becoming Test Car “Iris” ) including testing of radio equipment a role which saw the interior totally altered. M79901 became surplus to requirements, deemed surplus and scrapped at her home depot Bletchley TMD in April 1967. 

In 2000 79900 was withdrawn and entered preservation. “Iris” as she was known was fully rebuilt to original 1950’s specification by her new owner and made her first runs in preservation at the Midland Railway Centre in 2004. Iris retains her now rare AEC engines (rather than the standard Leyland) but has been modified for air supply and can now work in multiple with “blue square” fitted DMU’s.  

She is now part of the Ecclesbourne Valley DMU group fleet and in Sep 2022 was on loan to the GCR under the custodianship of Renaissance Railcars.

Sample Workings

79901  1230 Bletchley – Banbury MS 161057

79900/79901  1630 Buckingham MS – Banbury 060860

79900  1230 Bletchley – Banbury MS 250860

79900  1355 Banbury MS – Buckingham 250860

79900  1304 Bletchley – Buckingham 181161

79900  1600 Bletchley – Buckingham 180864

79900  1635 Buckingham – Bletchley 180864

79900    Bletchley – Buckingham all day 050964 (last day of Buckingham branch) 


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