Sometimes, sometimes not. Some of the emperors had large tombs built (Hadrian's tomb survives to this day) but their remains were cremations. A bunch of the fatalities of Vesuvius in 79 AD were burials, but that was extemporaneous...
By 410 AD, when this person was buried, the Western Roman Empire (including southern Britain) had been Christianized, and the Christian faith has historically opposed cremation because of its link with paganism and the promise of a bodily resurrection of the believers "asleep in Christ". Given the time frame, burial rather than cremation would have been the norm.