there already is a Commonwealth in our part of the world - it's called Australia and NZ has a constitutional right to rejoin.
Adam Bogacki, Sydney. firstname.lastname@example.org
P.S. The Latin 'res publica', literally 'thing public', is often translated in modern terms as 'republic', but also as 'common wealth'. The first Commonwealth in the English-speaking world was Cromwell's which has received a slanderous press ever since the Restoration - you should read some of the virulent royalist tracts of the time. Tom Paine was banished and his books burned for suggesting an English republic after the American revolution (but before the French). Not much has changed since. Now, however, Britain is no longer an imperial power and as a member of the EU has to confront the unpalatable fact that much of its history since Waterloo puts it at odds with the other members, many of which are republics. It can be argued that republican ideals of inclusion are now taking on a new currency.
Have a look at John Keane's "Tom Paine: A Political Life", Bloomsbury, 1995.