Plagiarism is rife in British schools and Universities and even Oxford is having a problem. Why fight it? Why not accept that the assessment procedures have to change to reflect the real world?
Let students use the internet and google to prepare themselves for work where these skills wil be neccessary, but assess them under exam conditions, live, testing their search skills and their subsequent analytical skills under the scrutiny of an examiner. That way they cannot use prepared work or other peoples’.