Isles, making Donald Stewart the party's only MP. This was to be the case until the 1973 by-election at Glasgow Govan where a hitherto safe Labour seat was claimed by Margo MacDonald. 1974 was to prove something of an annus mirabilis for the party as it deployed its highly effective It's Scotland's oil campaign. The SNP gained 6 seats at the February general election before hitting a high point in the October re-run, polling almost a third of all votes in Scotland and returning 11 MPs to Westminster. Furthermore, during that year's local elections the party claimed overall control of Cumbernauld and Kilsyth. This success was to continue for much of the decade, and at the 1977 district elections the SNP saw victories at councils including East Kilbride and Falkirk and held the balance of power in Glasgow. However, this level of support was not to last and by 1978 Labour revival was evident at three by-elections (Glasgow Garscadden, Hamilton and Berwick and East Lothian) as well as the regional elections. This was to culminate when the party experienced a large drop in its support at the 1979 general election, precipitated by the party bringing down the incumbent Labour minority government following the controversial failure of that year's devolution referendum. Reduced to just 2 MPs, the successes of October 1974 were not to be surpassed until the 2015 general election. In 1979 the party's MPs supported Margaret Thatcher's Motion of No Confidence in James Callaghan's Labour Government, with the motion carried by 311 votes to 310. Callaghan taunted the party that they were like "the turkeys who voted for Christmas" and the party went on to lose all but two of its seats in the subsequent election that ushered in 18 years of Tory rule. Factional divisions and infighting (1980s) Following this defeat, a period of internal strife occurred within the party, culminating with the formation of two internal groups: the ultranationalist Siol nan Gaidheal and left-wing 79 Group. Traditionalists within the party, centred around Winnie Ewing, by this time an MEP, responded by establishing the Campaign for Nationalism in Scotland which sought to ensure that the primary objective of the SNP was campaigning for independence without a traditional left-right orientation, even though this would have undone the work of figures such as William Wolfe, who developed a clearly social democratic policy platform throughout the 1970s. These events ensured the