A question of enforcement

Let me repeat a question I asked earlier in the month. Why are drivers being allowed to get away with parking for hours at a time in Rosebank Villas E17, across the pedestrian zone which forms the main passenger route to and from the High Street leading to Walthamstow bus station? This is a high profile area for parking enforcement. None of the vehicles involved is displaying a blue badge and the sign is very clear that no parking is permitted at all between 10am and 4pm, which is the time slot when I photographed these offenders on 23, 25 and 26 August.