 Complete the following phrase:  With Lotus signing Peter Arundell as Clarks team-mate for , Spence spent most of the early season driving in Formula Two events. However, shortly before the British Grand Prix, Arundell suffered a severe accident in an F2 race at Reims-Gueux, and Spence was called up to replace him in the F1 team for the rest of the season. Driving both the Lotus 25 and the Lotus 33, Spence managed points finishes in two World Championship races, sixth in Italy and fourth at the season finale in 