That is about as much as you would expect to find online at this stage of your research. To progress backwards you need to buy your grandfather's birth certificate from www.gro.gov.uk (£9.25 including postage) using the reference you found in the index. This will give you (amongst other information) the name and occupation of his father and the name and maiden name of his mother (the latter should be THOMPSON). Armed with this, you should be able to pinpoint their marriage in the GRO marriage index and send off for the marriage certificate. This will show the names and occupations of both their fathers and thus enable you to identify them on the 1911 census (and earlier).

I should just point out that, even at this early stage of your quest, you have encountered something that you need to be very wary of - dodgy data. For reasons best known to themselves (!) Ancestry have incorrectly "inferred" a county for Bertie's birth. Northampton is (unsurprisingly) in Northamptonshire, not Cambridgeshire.