In answer to Ros on 25th Sept, yes you can have conservation area without Article 4 direction. The council can impose an Article 4 on defined areas.

Our residents association is opposed to the changes, principally because of loss of permitted development rights, and have sent a letter to this effect.

Did you know, by the way, that if you apply for planning permission for something (e.g. single storey extension) that was previously permitted development, and the permission is refused, you can theoretically claim compensation from the local authority for any loss (say, in value of house).