You can email the HMRC bosses
HMRC don’t like using email and don’t normally publish individual email address on their headed paper.
They will tell you that they don’t use email for security reasons – of course HMRC do use email, they just would prefer it if you didn’t use email to contact them.
Why is this? Security might be something do do with it, but there’s also a tactical advantage for HMRC to get you talking on the phone. Also, they know how worrying it can be to get a brown envelope on a Saturday morning; it’s two full days to sweat before you can get professional advice.
Emailing HMRC gives you more control and is a more efficient way of communicating. The digital trail also reduces the lightly-hood of documents getting lost.
Once you know the full name of the individual it’s straightforward to work out the email address: its normally firstname.lastname@example.org so Permanent Secretary for Tax, Jon Thompson, can be mailed as email@example.com. He also has a twitter page here: https://twitter.com/jonthompsonmod.
You can get the directors’ names here.
Here is a list of HMRC people that may be useful.
If you can add to it do let me know through the contact page.