The English don't tend to see 1707 as the start of something new only as a small appendage getting added so British and English until recently were basically synonymous but the OTOH Scots needed the notion of overarching Britishness more than the English did to be able to maintain Scotland's own brand of Protestantism without being swallowed up into the numerically and economically stronger England. In the early years of the empire the Scots and English strands of Britishness fed off each other symbiotically to create a whole that was greater than the sum of the parts. The English provided the top-down cynicism required to build a great empire through things like divide and conquer and a rigid class system geared to overseas conquest, while the more egalitarian Scots provided the free thinking inventors and the missionaries like David Livingstone. The Scots were basically the true believers and high minded idealists in the "white man's burden" stuff and the Scottish elite was more than happy to ditch the Scots tongue and culture to be the junior partner in the imperial project as Scotland is a very small place and the empire provided loads of opportunities to the restless and ambitious.

Since the late 1800's though many/most Scots have felt cheated as the British state has slowly turned more and more into something resembling a unitary English 19th century style nation state through centralisation, secularisation, the end of Empire etc etc as for the Scots, Britishness was a multinational project based on an idealistic belief system and a shared set of democratic and moral values while for the English it was more a normal national based thing. As England is much bigger than Scotland and Scotalnd's elite agreed to a unitary parliament within an incorporating union, Scotland has been faced with the choice of assimilation into England by the 50's or 60's as Scotland traditional autonomy entrenched by the Union was brought to an end by the decline of the Church of Scotland in terms of social and political relevance and Labour's socialist centralism and the Tories retreat into Little Englander nationalism.

Scotland has basically said "no thanks" to being swallowed up into England but the problem is that Scotland is not that suitable ground for nationalism and building a new national ethos at the core of a Scottish nation state as a culture that willingly and consciously dispenses with it's national state language, Scots, and reduces it to the level of a stigmatised working class vernacular to build a larger imperial project is not for a 19th century style nation state building project. The whole imperial process made Scotland a very fragmented society in which there was no strong coherant sense of shared national identity amongst people from different social strata and ancestral backgrounds. Jorg Haider has described Austria as "an ideological miscarraige". Scotland vis-a-vis Britain is maybe not that dissimilar to Austria vis-a-vis Germany in some ways IMO except it did not become a separate nation state in 1918 for reasons of geostrategic expediency when the old pre-national relic of Austria-Hungary collapsed into separate nation states. If the British Empire had collapsed in the early years of this century, Austria_hungary or Soviet Union style, Scotland would IMO have been a Belarus or Austria yearning for anschluss as it would have been more empire-nostalgic than the original core-state clinging to the old system mentally as it lacked the cultural and social resources to do something different and new while everybody else was better able to move on into the future.

Some cultural nationalists try to create a Scottishness that is radically different from Englishness by trying to take over Gaelic from the Highlanders/Hebrideans after centuries of trying to eradicate it along with all the Celtic cultural stuff. It doesn't work for most people though as it is based on a lie about Scotland's history that the Scots were all somehow a subject people and a colony of England while in fact we were often in many ways the true believers and the ideological hard core of the British imperial project. The problem for the SNP is that independence should have long since happened by now but Scotland has been unable to do it because although people in Scotland are not comfortable with the modern manifestation of Britishness they are not readily able to build something else to replace it as Scottishness has yet to fully develop significantly beyond the immature "ah'm no ****in English" level to a depth and level of intellectual sophistication that would sustain a separate state from the rest of Great Britain. 250 years of trying to be more ratherv than less like your neighbour and a cultural cringe that all things English are somehow better than all things Scots does that to people. The Daily Record "ah'm feart" cartoon before the 1979 referendum basically sums it up although things have moved on a bit since then fortunately. Maggie Thatcher in many ways greatly helped the development of the new Scotland as Marco Biagi and the St Andrews Uni SNP have pointed out by making her an honourary life member of their club.

The problem for people like Yasmin Alibhai-Brown OTOH is that they want a Britain based on a set of ideals not on blood and soil while in contrast people in Scotland are cheesed off with Britain precisely because it has become too much of a unitary nation state and has left behind the overarching multinational set of ideals as a core raison d'etre. People in Scotland have an escape route via the Scottish component of their traditional dual Scottish-British identity while people like Yasmin Alibhai-Brown don't. they are stuck with Westminster and the consequences of Scotland breaking away to do its own thing. The solution IMO is that the SNP has to begin to talk up more positively what the future landscape of the British Isles would be post-independence and propose constructive models of future cooperation rather than basing its appeal primarily on negativity about the status quo and destroying the old order based on a phoney revisionist nationalism. By doing so it would recreate the dual Scottish-British identity which best suits Scotland by helping to redefine modern Britishness to something more multipolar and multicultural thus enabling both Scottish and British society to more easily move on into the new European future through somthing like the Nordic Council based on something like the Council of the Isles in the Good Friday Agreement.

Personally I don't think it is going to happen in the short term. It will take ca. 20 years maybe for a new self-confident political culture to take root at Holyrood as the foundation for a new set of mature intra-British relationships that will replace the imperial era way of doing things to develop. People first need to move beyond the stage of seeing any continuing manifestation of Britishness as being assimilative Englishness in all but name and to be a lot more secure in their sense of Scottishness. If people like Yasmin Alibhai-Brown could see a destination that was not going to be a set of Balkanised mutually antagonistic 19th century style nation states based on a racial foundation myth but rather something like the relationship between liberal egalitarian modern secular civic states like Norway, Sweden and Denmark maybe they would be a lot more comfortable with the SNP and what it is trying to accomplish through the dismantling of the old unitary centralised Britishness of the past?