Strange that Halfords don't sell Castrol grease anymore. They used to be owned by Castrol-Burmah oil company; don't know if that's still the case.
BP bought Castrol a few years back.
BP took over all the Mobil Oil petrol Stations in the UK in '96 which just left Mobil Oil as an oil producer mainly around Birkenhead. Mobil Oil then merged with Esso (Exxon) a couple of years later and now pay my pension. Funny old world when the 7 sisters of the oil world mostly end up in the same bed.