Having only been closed on average a few times a year since its commissioning in 1982, I read that the latest March closure was the 48th so far in 2014, very close to the recommended annual limit of 50. This certainly tells me something about flood risk.

With the recent storm surges on tides in the English Channel, I imagine it has provided a great feeling of security to Londoners.

The Barrier was a big project in its time. The four main gates which make up the barrier are each as high as a five storey building and at 61 metres are as wide as the as the opening of Tower Bridge. The gates are operated by three 140kW hydraulic power packs with their own generating sets. Not surprisingly, the cylinders are pretty substantial, having a piston of 1100mm diameter and rod of 431mm diameter with seals from James Walker. For a refresher on the Barrier in action, have a look here. Much as I would love to have supplied Micropac standby hydraulic hand pumps, I think you would be pumping for a very long time. For other hydraulic applications, look at www.sarum-hydraulics.co.uk.