DIfficult to be sure, but there's a fair chance it is Raphidonema faringdonense. The type locality is Faringdon, Oxfordshire (Aptian, Cretaceous).
The species is often spelled Raphidonema farringdonense (two 'r's), and since the River Dever runs quite close to Farringdon (two 'r's), Hampshire, you could be forgiven for thinking your specimen came from close to the type locality.
(Such mistakes are scattered throughout scientific nomenclature, eg. there's a snake bark maple called Acer pensylvanicum (one 'n'), named after the state of Pennsylvania (two 'n's).)
- There are other species in Raphidonema: eg. Rr. contortum, macropora, nivale, pustulatum.
- I don't know if Raphidonema extended to later in the Cretaceous (such as the Newhaven Chalk around Micheldever: Santonian-Campanian, 71-86ma). I am having difficulty finding similar sponges in that timeframe (Porosphaera does not really fit).