The route to Cleethorpes promenade was full of opportunities for challenge. We crossed the railway bridge and walked at the edge of the beach where a fence of upright wooden railway sleepers divided it from the railway. Over the years some had decayed and some were missing. This meant that the walk along the tops of them featured occasional gaps that had to be jumped. When three in a row were missing it meant quite a jump, too, onto a very small surface.
The real challenge was the row of concrete blocks that went up to the base of the promenade. These were World War II anti tank defences, huge concrete cubes, a few feet square and high. They faced each other diagonally so you could jump from a corner of one to the near corner of the next if they were close enough together. Not all of them were. There were over a dozen of them in a row that gradually got higher as it followed the rise of the beach up to the promenade at the end.
Of course we jumped them. We couldn't clear all the gaps, so there were points when we had to drop down onto the sand and climb up the next one instead of jumping between them. Another problem was that the sand under some of them had shifted, causing a few of them to lean at crazy angles. As we grew, we were able to jump one or two of the more challenging ones and clear most of them along the tops. A miss would have meant injury, maybe just a grazed knee, but maybe a broken ankle. We gradually acquired the longer legs and the skills to jump all of them at speed on the way down, but there was always one of the leaning ones whose gap was too large to clear on the way up.