 Despite Kneale 's reservations about the casting , The Quatermass Xperiment was the highest @-@ grossing film Hammer had made up to that point in their history , and has since been described by one academic as " the key British science fiction film of the 1950s . " Hammer were keen to make an immediate follow @-@ up , and wanted to use Quatermass in their 1956 film X the Unknown ; however , Kneale refused them the rights , and they created their own substitute character , Doctor Adam Royston . They did release an adaptation of Quatermass II in 1957 , called Quatermass 2 and this time with Kneale 's involvement in the script . To the writer 's displeasure , Donlevy returned as Quatermass . 
