You can only be sure with the Conservatives :  the Conservative manifesto 1997. 

 - London :  Conservative Central Office,  [1997] 
<br/><br/><label>ISBN: </label>0850709261 
<br/><br/><label>Subjects--Corporate Names: </label><br/>Conservative Party (Great Britain)--Platforms, 1997.<br/>Great Britain. Parliament --Elections, 1997.
<br/><br/><label>Subjects--Topical Terms: </label><br/>Campaign literature--Great Britain.