London is not a country. The analogy only works if you start from the position that Scotland is not a country with no right to self-determination any more than a city within a state. Even staunch unionists such as Blair and Cameron acknowledged that Scotland is a country and could decide to leave the United Kingdom if it wishes. Comparing Scotland to London should be just as insulting to self-respecting unionists as it is to those who support independence. Because don't unionists claim that we are a family of nations that come together voluntarily?
In Australia all the regions need to agree to a change in the constitution for it to pass. (For example one state could prevent the abolition of the monarchy even if a majority of people voted in favour across the country) Why is Scotland regarded as less than a region of Australia? If all the regions of Australia need to agree a change in the constitution, why not all countries in the UK need to agree before we do anything as drastic as leave the EU?
When Scotland voted in 2014 it was promised we would be equal partners in a more federal system. If that were true our vote to remain in the EU would count.