The author caught up with these stalwarts in their latter years when they were being operated by Railtest and took part in several test series with both units.

Iris 1 was originally built as a two-car Derby Lightweight DMU in 1954 and was later converted into two single cars. This contemporary article from the September 1956 issue of the London Midland Region magazine describes the intended use of the single car unit M79900 on the Buckingham branch. John Spencer Gilks also has a number of photographs of M79900  in his excellent trilogy of books 'Dawn of the Diesels'.

It was used by the R&DD for radio survey work and also general testing and was originally painted in the Division's red and blue livery and designated 'Test Coach Iris '.

In its later years the unit was re-painted into BR green and carried both its original running number as well as its Departmental one. Luckily it was never painted in Serco's red and grey livery.

In 1997 I was involved with Iris 1 when it was used to undertake a rush job related to 3rd rail shoegear clearance on the WCML. There was a new service to be introduced between Rugby and Gatwick service using dual voltage class 319 units. Although WCML had been gauge-cleared for Eurostars (which had retractable shoegear) somebody forgot that 319's didn't and there were doubts about the lines between Rugby and Bletchley. I recollect spending the some time pottering between these two places via the main line and via Northampton during a very hot July. Iris 1 was very compact having a diesel generator squeezed into the guard's area and a kitchen and a couple of seats in the opposite end. The main instrumentation area took up most of the vehicle. It rode like a pig at 75 mile/h but luckily we didn't go that fast very often!

Iris 1 is now retired and was very nicely restored at the Midland Railway Centre, Butterley Derbyshire to virtually original condition and was used occasionally in passenger service on the MRC.

In early 2008 it made a visit to the Churnet Valley Railway and then to its new home on the Ecclesbourne Valley Railway where it runs regular passenger diagrams most weekends. For more information see the railway's site at www.e-v-r.com.

Here is a selection of photos of Iris 1

Click on the picture for a bigger image - photos are the author's where not credited

Iris 2 was converted in 1991 from a power twin unit at the R&DD to a high standard as a test train known as "Lab 19 - Iris II" which it always had displayed on its destination blinds. It was completely re-furbished inside. One vehicle was equipped with a diesel generator set, kitchen and eating area and an instrumentation area with air conditioning . The other vehicle was not to the same high standard but had a small workshop and storage area and bunk beds for the use on night work when stabled. I remember once spending the night on Iris2 at Reading depot when the night job was cancelled and we had no hotel.

Work undertaken on Iris 2 when I was first involved included radio survey work in connection with the NRN which was regularly undertaken particularly on the GW and Southern Zones of RT. Later Iris 2 was chosen to undertake pioneering video surveying of the whole railway,  which included all lines from Penzance to Thurso. I remember one trip from Clapham Junction Yard to Penzance Long Rock depot - all the way down the old LSWR main line in the cab! Happy days.

We also undertook a signal sighting survey prior to the WCML upgrade on all lines between London and Glasgow including diversions. This was in connection with raising the speed to 125 mile/h.

Iris 2 was retired at the end of the 1990's but was back in action in 2004 conducting yet more radio surveys. However, it had by then been given the all-over yellow livery favoured by Network Rail. At least it looks better than the hideous Railtrack livery of lime green and dark blue.

In late 2007 Iris 2 was finally retired and was offered for sale. In March 2008 it moved to the West Somerset Railway at Dunster, where it is now painted green and used by the Permanent Way Department.

On August 17th 2009 The West Somerset Railway unofficial site (wsr.org.uk) had the following information 

"IRIS II heads for Wales The two-car DMU IRIS II is about to leave for Wales. It has been stored unused at Dunster Yard for over a year. During that time the DMU - Network Rail Laboratory 19 IRIS II test train 901002 - was repainted by its owner from yellow to a more heritage style green livery. Recently towed to Minehead, the DMU will be moved to Bishops Lydeard in a few days, thence transported by road to Barry. WSR General Manager Paul Conibeare commented "The owner, John Buxton, is removing it to Barry to run services on the new railway, which John has just taken over. We wish John all the best with his new venture and I am sure IRIS II will be a popular and useful vehicle."