Clearing out old transactions

[Henry Law]

I run the domestic accounts as a single GNUCash file.  After the end of 
the tax year (5th April in the UK, for good but obscure reasons) I 
reconcile everything and then use the "Close Books" facility to clear 
out all the expense and income accounts.  I place the balancing 
transactions in a pair (income and expense) of accounts called "Expense 
2014-15" and "Income 2014-15" (for example).

I've been doing this for some years now, so I have lots of entries which 
are no longer of any relevance in themselves: they've been accounted for 
as income or expense and their effects have been moved to the annual 
accounts as described above. I want to delete them.

I've looked at gcCull.pl and (with apologies to its author) I'd like to 
understand the process it enables before using it.  So I've established 
a very simple scenario and I'm trying to work out how the deletion 
works.  Can someone help me work through this?

My simple example is at 
http://www.lawshouse.org/misc/DeleteOldTransactions.pdf  In it you will 
see that I had one expense in 2014-15 and one in 2015-16.  I've shown 
the accounts affected.  If I simply delete the transaction of 6 May 2014 
my net worth will be off and the whole thing won't balance.  (Isn't that 
what gcCull.pl does?).  It seems to me that I need to reflect the £100 
reduction in net worth by reducing the "Opening balances" account with a 
Debit, as shown in the bottom line.  But am I right in thinking that the 
corresponding Credit would be to the "Expense 14-15" account?

It seems to me, therefore, that for each transaction to be deleted the 
steps are these:

1. Adjust the opening balances downwards by a Db for the amount (or up 
by a Cr for an income that I'm deleting)
2. Make a balancing transaction in the "Expense" or "Income" account for 
that year
3. Delete the offending transaction.

In practice I'd do this for lots of transactions, and make only one 
adjustment to the "opening balances" and one corresponding one in the 
appropriate "14-15" account.

Have I got this right?

-- 

Henry Law            Manchester, England