Located in south west London, this museum features the largest working triple-expansion steam engine in the world, so when I discovered they were having a steaming day while I was in London, I had to visit.

The building was constructed in 1928 and housed two large triple-expansion steam engines which were used to pump the water uphill to a reservoir at Cricklewood:The engines were shut down in 1980 and electric pumps on the site still send the water to Cricklewood.  One of the engines has been restored to working order, while the other one is available for tours.  This is the working one, you can get an idea of the scale from the people on the ground level.  This picture was taken from the top walkway of the other engine:Round the back of the working engine this is one of two “barring engines” used for starting:In the 1930s when the time came to expand the capacity, instead of adding the planned third engine in the space between the others, two more modern steam turbines were installed.  Surprisingly, these could pump about the same amount of water as the big engines:(Yes, they had visiting Morris Men!)The site generated its own electricity, and still has a couple of mercury arc rectifiers in operation.  The flickering glow of these holds a strange fascination:I must say I had expected a fairly quick in and out, half an hour should easily cover everything, but the guided tour of the non-working engine took well over an hour, all of it fascinating.

One fact I learned from the tour guide is that the two engines are mirror images of each other.  This must have meant that when the factory made a casting for a part, instead of making two the same – one for each engine – they had to make mirror images.  The only reason I can think of is it made the engine hall more aesthetically pleasing.  Part of the spare-no-expense attitude of the time perhaps; apparently the opening ceremony was catered by Fortnum & Mason.  I wonder what they would have done for symmetry if the planned third engine had been installed in the middle.

A final picture, of the crest and at the bottom the gauges that still show the flow of water to Cricklewood.  The “hoops” displayed on the wall below the crest are spare piston rings from the three sizes of cylinder in each engine:

Chiltern Railways operate trains from London Marylebone to Aylesbury, Oxford and Birmingham.  In addition to their main routes they are responsible for the short branch line between Princes Risborough and Aylesbury.

Faced with a shortage of trains a few years ago they acquired some single car first generation diesel units, known to railway enthusiasts as bubble cars, and refurbished a couple to use on this branch line during rush hours.  This released a longer more modern train to operate elsewhere.

It has been reported that the bubble cars will cease working in the May timetable change, so I decided to go for a farewell ride on the oldest passenger trains on the mainland rail network.

The empty bubble car arrives at Princes Risborough to commence its afternoon duties:Ready for passengers at Princes Risborough:The other end of the route at Aylesbury:The guard on the service seemed unsurprised that half the passengers were railway enthusiasts there for the ride, in fact he invited us to do another round trip.

A final picture in the darkness at Princes Risborough:There were other things to see at Princes Risborough while I waited for the bubble car:  Just to show that Chiltern isn’t all about antique trains one of their expresses whizzed through, hauled by one of the newest locos on the network, a class 68.  (Sadly it was a bit too fast for my photographic skills.)And on the other side of the station, the Chinnor and Princes Risborough Railway were working extending their preserved line to a new platform adjacent to the main station which they hope to open later this year: