This originally caught my interest because it all looked wonky. After posting on Twitter it was highlighted as a phase transposition by @DiverTomJG

“The majority of double CCT lines are transposed by having different phasing on each CCT. Line transpositions are only really seen on the original 1930’s 132kV grid lines which were predominantly long distance single CCT.” @DiverTomJG

“This DC tower was built at a later date and is an addition to the original line. I would guess its addition was to increase the ground clearance to allow them to build the housing estate below.” @DiverTomJG