A farm at Calcethorpe near Louth was broken into and a set of keys stolen.
According to police, the thieves entered the farm at about 10.50pm and the owner of the farm returned at 11.05pm and it is believed this disturbed the intruders.
PCSO Sally Hewitt of Louth Rural neighhourhood policing team said it is possible that a small blue vehicle was being used by the thieves and is appealing to anyone who has information regarding this vehicle, referring to incident 40 of November 2.
She urges farmers to review security of farm buildings.
She said: “Please ensure that any security lights are working and in order. With regards to any CCTV, please check that your cameras are working, check they are recording and the images are not obscured by any dirt/cobwebs, etc. Please report any suspicious behaviour immediately on 101 or 999 in an emergency.”