Embedding HTML in Gridview HeaderText

[Paul]

I am trying to embed HTML in a gridview's HeaderText field.

Something like this:
<asp:BoundField DataField="rfq_4567_count"
HeaderText="RFQs<br>(4-5-6-7)" SortExpression="rfq_4567_count"
HtmlEncode="true">
<ItemStyle HorizontalAlign="Center" />
<HeaderStyle HorizontalAlign="Center" />
</asp:BoundField>

But the HeaderText won't give me a HTML <br> linefeed.

Can this be done?