I ran this past a friend of mine, who is conversant in PHP, and this is how he solved it...
First, on the contact page, a call to a custom snippet, and an amendment to the FormIt parameter for the emailTo field:
[[!MyFormIt]]
[[!FormIt?
&hooks=`spam,email,redirect`
&emailTo=`[[+emailto]]`
&redirectTo=`1`
&validate=`
name:required,
email:email:required,
subject:required,
text:required:striptags`
&validationErrorMessage=`<h4>Please correct the errors in <span class="red">red</span></h4>`]]
Note the cunningly name custom snippet - MyFormIt !!
Here is the code in the snippet:
Finally, the change to the <select> element is:
<option value="1" [[!+fi.addressTo:FormItIsSelected=`1`]]>Chairman</option>
And bingo! The email sends, but the address is not in the rendered HTML!
:D