Two years ago there was a fascinating (well, I found it fairly interesting) debate in this forum about how to deal with purchases made by a VAT registered company from a non-VAT registered trader. Here is the link: http://www.book-keepers.org.uk/t44104911/still-need-convincing/
Personally, I use T9 when recording purchases from non-VAT-registered traders made by our VAT-registered company. But there are other opinions.