~What of the restriction?
The s19 power can only be exercised when the officer has reasonable grounds for believing in relation to such the 'evidence', "that it is necessary to seize it in order to prevent the evidence being concealed, lost, altered or destroyed." Curious that Sussex police, though careful to make use of s23 (and constructing it rather too broadly) to justify themselves as far as "premises" are concerned, seem not to have been interested in justification against the "necessary" criterion. Necessary is quite a strong word.
Which of concealed, lost, altered or destroyed did the officer believe was going to happen? He had to have some reasonable grounds for believing at least one of them.