In the end I managed to get it working with the following flows.
I created a helper bean to hold a function for adding to the list held in the form bean.
<view-state id="page2" view="page2">
<transition on="save" to="addToList">
<action bean="form" method="bindAndValidate"/>
</transition>
<transition on="back" to="page1">
<action bean="formAction" method="bindAndValidate"/>
</transition>
<transition on="next" to="page3">
<action bean="formAction" method="bindAndValidate"/>
</transition>
</view-state>
<action-state id="addToList">
<bean-action bean="helperbean" method="addToList">
<method-arguments>
<argument expression="conversationScope.form"/>
</method-arguments>
</bean-action>
<transition on="success" to="page2"/>
</action-state>
It then displays the original page again