DMU at Harrow On The Hill

Not realy sure this is preservation. However it is certainly heritage. Passing through Harrow on the Hill yesterday at around 1630. I saw a heritage DMU in the platform. I guess it was a converted Cl115 doing Sandite duties.
Anyone got any further information. Thanks in advance

 

Was it a green liveried 3-car?

If so, it will be the Chiltern Railways Class 117 Water Jetting unit, 960301. Funnily enough, there is a preservation link with this one. The powered centre car, ex 51375, used to be a preserved driving vehicle at the Birmingham Railway Museum, it had its cab chopped off at LH Group in 2004 after being resold to the mainline (Chiltern).

 

Indeed it was. I did not get a good look at it, and did not see the centre car at all. I had to go to Aylesbury today, and did not see it hanging about there. In fact the only heritage DMU was a blue and grey bubble car, which looks like it is also used for railhead treatment duties.
How times change I used to live in Banbury where 115/117/121 DMU's were an every day sight. Now a 3 car 117 on the mainline is worth talking about.

 

The Blue Grey Bubble Car is 960014, which is used for route learning duties.