... The normalised WHT optical spectrum of KIC 10449976 fitted with the model described in 3 optimized for abundances of C, N, Si and Ne, together with line identifications. ... Optical spectroscopy of the blue star KIC 10449976 shows that it is an extremely helium-rich subdwarf with effective temperature T eff = 40 000 300 K and surface gravity log g = 5.3 0.1. ... Kepler photometry of KIC 10449976 in both long and short cadence modes shows evidence for a periodic modulation on a timescale of 3.9 days....