legal requirement on stock control and inventory systems

What is the legal requirement on having stock control and inventory systems for the purpose of VAT. Is stock control compulsory for specific industries, if so which ones? If you don't have inventory systems is this illegal? How does this affect our VAT returns. Please enlighten me on this.

 

Hi. Please see the guidance below which details the records and accounts which need to be kept for VAT purposes: Record keeping (VAT Notice 700/21)  . Thank you .