I think an adjudicator would throw this out on triviality grounds but this is what the traffic order says - note 'enter... within a 2.5 metre gap'.
Note: York Road is a dead end and has parking bays so reversing out may have been the best way to turn around and obey the second and third extracts from the experimental order.
But mind the gap!
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2. Prescribed Routes
2.1 No person shall cause or permit any motor vehicle to enter or proceed in Adelaide Road, E10, within a 2.5 metre gap between the intersection of the north eastern kerb line of York Road and north western kerb line of Adelaide Road (outside No. 42 Adelaide Road), and the intersection of the south western kerb line of York Road and south western kerb line of Adelaide Road (outside No. 27 Adelaide Road).
2.4 No person shall cause or permit any motor vehicle:
(vi) travelling north-westbound in York Road, E10 between its junctions with Ruckholt Road E10 and Adelaide Road E10 to enter that section of Adelaide Road E10 north-west of the southeast kerb line of Adelaide Road except to turn north-east into Adelaide Road;
2.5 every person causing any vehicle to proceed:
v) in York Road E10 between its junctions with Ruckholt Road E10 and Adelaide Road E10, shall cause that vehicle on reaching its junction with Adelaide Road E10 to turn right only;
https://store.traffweb.app/walthamforest/documents/parkmap/sched/ET8(25)%20Experimental%20Traffic%20Orders%20(ETRO)%20-%20Oliver%20Rd%20to%20HRL%20traffic%20imps.pdf