Complex sentence: It is named after the 18th-century Howden House, which was derelict but it has been converted into 5 small flats during 2012/2013, although the adjacent stable block has been converted into the Howden Park Centre, an arts and entertainment venue.
Split into simpler sentences: It is named after the 18th-century Howden House, which was derelict but has ewcently been converted into 5 small flats during 2012/2013. The adjacent stable block had previously been converted into Howden Park Centre, an arts and entertainment venue.