The walk starts from the northern end of Heatherdene car park on the A6013 beside Ladybower Reservoir (S33 0BY), which is run by Severn Trent. It's pay and display: £3.50 for up to 2 hours, £6 for 2 to 4 hours or £7 for over 4 hours, paid by cash or card at the machines or with the RingGo app (zone 58250). It's open in daylight hours only, with no overnight parking, and closes in extreme weather. It's popular, so arrive early at weekends. There are toilets in the car park. Please don't use the Yorkshire Bridge Inn's car park, which is for the inn's own customers. Check the latest prices here.

In 1862 the writer William Wood set down an old local tale in his book Tales and Traditions of the High Peak. It begins in the year 626, with Edwin, King of Northumbria, at war with the West Saxon kings Cynegils and Cuichelm, who had Penda of Mercia on their side. According to the story, Cuichelm sent a man called Eumer to kill Edwin with a poisoned dagger, but one of Edwin's attendants, Lilla, stepped in front of the blade and was killed. Edwin then marched against them.

The two armies camped on the hills either side of the River Noe, Edwin's Northumbrians on Win Hill and their enemies on Lose Hill. Edwin had fewer men but the better ground, and they built a long wall of stones near the top. After hard fighting in the valley his army fell back behind it, and as the enemy climbed up after them they rolled the stones down the slope and crushed them. The enemy kings fled, Edwin lost nearly half his army, and the two hills were named after the winners and the losers. Wood added that bones were said to have been found by the river, and that the stones were later cut into millstones.

Even Wood said nobody could vouch for the tale, as it rested on word of mouth, and there is no evidence that any battle was fought here. The real story of the name is probably much gentler. Win Hill was once written down as Wythinehull, which likely means Withy Hill or Willow Hill, and bits of willow can still be found among the conifers on the climb from Yorkshire Bridge, the way this walk goes up.

The dam you walk across at the end of this walk took eight years to build. The Derwent Valley Water Board started work on Ladybower in 1935 to add to the Howden and Derwent reservoirs further up the valley, as the towns and cities it supplied needed more water. When war broke out in 1939, workers and materials became hard to find, but the job carried on because the water supply was so important. The dam was finished in 1943 and then took about two more years to fill.

Unlike the stone walls of the two older dams, Ladybower's is an earth bank with a clay core, and instead of water pouring over the top it has the two round overflows known as the plugholes. Materials came in on the Water Board's own railway, and part of its line is now the Thornhill Trail, which you walk along early in the walk. The reservoir drowned the villages of Derwent and Ashopton, and most of the people who lived there were moved to a new estate at Yorkshire Bridge, which this walk passes through on the way out. In a TV documentary in 1966 they had mixed feelings about it, though the move had at least meant the end of paraffin lamps and outside toilets.

On 25 September 1945, King George VI and Queen Elizabeth came to open the reservoir, and a crowd of around 25,000 people turned out to watch. The King unlocked the gates on the embankment and opened the valves to let the water flow. In the 1990s the dam wall was raised and strengthened so that it would be less likely to be overtopped in a big flood.