This is the approximate suburb or district boundary of Pokesdown today, as of March 2021, based on where the council marker signs are, and the northern boundary of the “Lower-layer Super Output Area E01015276”, called “Pokesdown Station”.
Looking at postcode boundaries, some of Pokesdown is in BH7 and some is in BH5. The southern edge of BH7 takes in Christchurch Road, from Ashley Road in Boscombe, all the way along to past Castle Lane East. BH5 runs south of the Christchurch Road from Boscombe Spa Road to just past Seabourne Road. BH6, which is east of, and including, Southbourne Road, is probably just outside of the Pokesdown suburb.
A reminder of the 4-in-1 Venn diagram style map, showing four of the different boundaries over-laid: