Shipping taxed twice when paying with NoChex

[BobD]

After upgrading from 1.5.1 to 1.5.5a I encountered the tax missing from shipping bug and applied the fix found here - https://www.zen-cart.com/showthread....61#post1312461
Everything is working fine for transactions involving Paypal payments and cheque/moneyorder payments.
However, I also have the NoChex payment module and strange things happen with transactions via that route. When the customer goes through checkout they are presented with correctly taxed goods and shipping and pay the that total through NoChex.
With the transaction complete the email order confirmation shows the correct tax-inclusive shipping total (e.g. £1.75 for the UK) but the Order Details in admin and the invoice show a double taxed shipping charge (e.g. £2.10 for UK) with correspondingly inflated tax and overall total.
Any guidance appreciated.

[swguy]

Follow ups to https://www.zen-cart.com/showthread....ead-Nochex-APC