There are very few Deeds (in the traditional sense) left.
Land Registration now means that whenever there is a transaction on a property it has to be recorded at the Land Registry. So all property details now include this stuff. Although often there is no reference to boundaries!
Although there are some Deeds about where land is unregistered. These will normally be in the hands of the owners, their solicitors, their bank or their mortgage company. There are also quite a few in the hands of record offices.
Did you have a boundary dispute in mind?