This question was posed by Lewison LJ in Cherry Tree, a case discussed in Chapter 12. This question clearly requires you to take a view on interpretation as well as rectification. If you think that interpretation should have a very broad scope, then you might be prepared to allow that common law doctrine to swallow up the equitable doctrine of rectification. There is obviously more room for rectification to operate if interpretation is more narrowly defined. But in any event, there might be good reasons for maintaining rectification still; some of these were discussed in Cherry Tree, and also pointed out by Lord Neuberger in Marley v Rawlings. Of course, you might argue that such considerations (such as taking into account pre-contractual negotiations and third party rights) could be accommodated by the common law of interpretation, but you would need to examine critically whether this would be desirable.