I've been doing a bit of reading about this subject lately and I did come across some information about when such a siege economy policy was actually countenanced (and I mean seriously considered, not just promoted by the Bennite hard-left).
In 1968, after the 67 devaluation of the pound and continuing balance of payments problems, the Wilson Labour Government did consider a plan known as Operation Brutus, which would have implemented many measures similar to a siege economy. There were 3 stages to this plan and Stage 3 was the most severe to be only implemented if Stages 1 and 2 were unsuccessful. Rather suprisingly Brutus 1 and 2 contained some rather (for their time) free-market ideas such as floating the pound, in order to restore an acceptable balance of payments situation. Only if this didn't work would Brutus 3 be considered.
One of the main features of Brutus 3 was an abolition of the distinction between Sterling and Non-Sterling areas. This would have been most noticeable for the average person in the fact that the very strict rules that applied for exporting currency to non-sterling areas would also be applied to sterling areas. The UK bank accounts of non-residents would be frozen. Special permission from the UK govt would be required for non-residents to gain access to these funds. Although there would be no explicit ban, this would institute a de facto ban on overseas travel for UK citizens resident in the UK at the time of Brutus 3. Currency would be alloweed to be used for expenses related to the conduct of international business, however personal travel expenses would only be permitted for compassionate reasons. It was suggested that the UK govt use the existing restrictions on monetary exchange with Rhodesia as a template for the implementation of Brutus 3.
The UK Cabinet had already got the Bank of England to investigate the ways international business transactions could be performed in a way that would allow the govt to maintain control over the broader balance of payments situation. It was envisaged that there would be some accounts that would be have no convertibility, some with limited convertibilty and a few which would allow complete exchange freedom.
Sorry if some of the above terminology is a bit unwieldy, but as said, I have more understanding of the political side of these things, rather than the exact financial terminology.
Whilst the Wilson govt was fully prepared to implement these strategies if necessary, they were also aware of the political implications. Even if the Tories had supported Operation Brutus (which probably in the short-term would have been necessary in order for the domestic British business community to accept it), Wilson did realise that ultimately it would destroy the Labour Party for at least a generation. However, he also felt at the time that there may be no other option.
LINKS:
news.bbc.co.uk/1/hi/special_report/1999/01/99/1968_secret_history/244316.stm
www.nationalarchives.gov.uk/documents/new_years_1999_pt4.pdf