Can I include this in a clearance letter?

I'm preparing a letter to send to a new client's previous accountant. From a meeting with the client I'm concerned that they should possibly be registered for VAT but they say that the previous accountant never mentioned it. Their income is split between grant income and business income but it's not obvious from the accounts what the split is. Would it be wrong to include a paragraph in the letter asking if the accountant has a monthly split of taxable/non taxable income so that I can establish when/if they need to register? It's not something that I would usually ask for but apparently he's been ignoring calls (hence him being sacked!) so I'm worried that if I don't ask in this letter I'll never get a chance again and then I'll have to go back through previous years files to get the bottom of this.
Thanks
Jodie