Watch Saving Lives at Sea Season 6 Episode 4 Online

The crew at Tower, on the River Thames in London, is the busiest of all the lifeboat stations, averaging more than 500 shouts a year and aiming to launch to any emergency in under 90 seconds. When a call comes in about a man in the water near the Thames Barrier, they reach him with just moments to spare. In Fleetwood, on the Lancashire coast, a desperate 999 call alerts the crew to a bait digger - out looking for worms on the sand flats - who has been caught out by the incoming spring tide and is in danger of being submerged and swept out to sea.