Thank you so much for your reply Shaun.
I was very excited to see this simple &usernameField property I had clearly overlooked, so I implemented it straight away.
Unfortunately it is not working for me, and is having the same result as the previous attempts I was making; ie. no username being set at all!
In my latest set up, in the register page I have:
[[!Register? &usergroups=`Members`&usernameField=`email`&activation=`0`&submitVar=`login-register-btn`&successMsg=`<p>New user [[+fullname]] with email address [[+email]] has been added!</p>`&usernameField=`email`]]
[[$lgnRegisterForm]]
And the lgnRegisterForm template chunk is:
<div class="register">
<div class="registerMessage">[[+error.message]]</div>
<form class="form" action="[[~[[*id]]]]" method="post">
<input type="hidden" name="nospam:blank" value="" />
<label for="email">[[%register.email? &namespace=`login` &topic=`register`]]
<span class="error">[[+error.email]]</span>
<input type="text" name="email:email:required" id="email" value="[[+email]]" />
</label>
<label for="password">[[%register.password]]
<span class="error">[[+error.password]]</span>
<input type="password" name="password:required:minLength=6" id="password" value="[[+password]]" />
</label>
<label for="password_confirm">[[%register.password_confirm]]
<span class="error">[[+error.password_confirm]]</span>
<input type="password" name="password_confirm:password_confirm=`password`" id="password_confirm" value="[[+password_confirm]]" />
</label>
<label for="fullname">[[%register.fullname]]
<span class="error">[[+error.fullname]]</span>
<input type="text" name="fullname:required" id="fullname" value="[[+fullname]]" />
</label>
<label for="company">Company
<span class="error">[[+error.company]]</span>
<input type="text" name="company:required" id="company" value="[[+company]]" />
</label>
<br class="clear" />
[[+register.recaptcha_html]]
[[+error.recaptcha]]
<div class="form-buttons">
<input type="submit" name="login-register-btn" value="Register" />
</div>
</form>
</div>
Any ideas why this is still giving me grief? I really thought it would be so simple to set the username the same as the email address!
Big thanks for any clues or hacks that can help me get this working

Toby