[r-t] Extent of Double Grandsire Doubles

[Richard Pullin]

James Ramsbottom asked:
> Is it possible to get a single extent (i.e. 120 true changes) of Double
Grandsire Doubles using only standard Grandsire calls?

Not possible for the same reason that you can't get a true 120 of normal
Grandsire made up from 3-lead plain courses. In Double Grandsire the bob
courses are also 3 leads long, so at some point you will run in to a lead
end repeating at the opposite stroke. In normal Grandsire the bob courses
are only 2 leads long, making true 120s possible.

Pitman composed three 240s in the method (probably the earliest examples,
as multi-extent blocks had only just been deemed acceptable - in fact, he
was one of the inventors and fighters for the concept.) The three 240s are
here https://grandsirerich.wixsite.com/ringing/doubles

> is there a 120 which almost meets the criteria e.g. has only 2 special
lead-end calls?

No, unfortunately it would take a bit more than that. Half lead calls would
be one of the neater ways, and you could get 4 mutually true blocks to form
a 120, but the difficulty is then joining the blocks together!
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