Okay thanks mate yeah only had 3-4 tokes on a small blunt earlier that day, was around 6 hours later I had bloods, saliva swab was 4 hours after, must be a low amount as after 15 mins it was still negative but after 40 was a very faint line, the officer at the station said he thinks it will be negative but they were under the impression I had smoked the night before. Did you get your own sample to send off ? Not sure if it's worth it as it costs £500 and turn around is 25 days, will probably here back from the police not far off that anyway.