“It will of course sometimes be possible for the prosecution to sub-divide an exhibit and serve only the part of it on which they rely as relevant to, and supportive of, their case: if a filing cabinet is seized by the police, but found to contain only one file which is relevant to the case, that one file may be exhibited and the remaining files treated as unused material; and the same may apply where the police seize an electronic database rather than a physical filing cabinet. Sub division of this kind may be proper in relation to the data recovered from, or relevant to, a mobile phone: if for example one particular platform was used by a suspect solely to communicate with his young children, on matters of no conceivable relevance to the criminal case, it may be proper to exclude that part of the data from the served exhibit and to treat it as unused material. But it seems to me that such situations will not arise very often, because even in the example I have given, fairness may demand that the whole of the data be served, for example in order to enable the defence to see what other use the defendant was making of his phone around the times of calls which are important to the prosecution case. The key point, as it seems to me, is that if the prosecution do wish to rely on a sub-set of the data obtained from a particular source, it will often be necessary for all of the data from that source to be exhibited so that the parts on which the prosecution rely can fairly be seen in their proper context.”