..... I knew if a mouse farted in my yard ...... came in one morning to find this ....... 
.... and if they had, would've set off me system 20 ft further into the yard ...... took some bloody straightening out they did 
Atleast they didn’t pinch your milk
...... 'kin bar stewards
Plot twist - Milkman forgot to put handbrake on
.... he'd have had to have been going some ..... have had a few buses clobber the gate posts .... my roadway was up through the centre of the bus station next to me ... bit of ice and the way those monkeys drove, then swinging right into their parking area ... IIRC the post has had maybe 9 or 10 over the years ... .... they were set in a metre of concrete ..... never had one o' them get bent
-- pikie an' a cordless. ...... been there all night BTLs breaking into a document safe, the size of a filing cab. with an open ended podgy spanner for a chisel and a 90mm dia 'cannon ball' as a hammer ..... 'kin workshop full of tools .. knobheads ... my five vermin control operatives who lived there. ...... well 'til 3 a.m. usually, which seemed to be tea leaf time but never lost another thing from the building or the acre yard ...... 4 grands-worth well spent ... and tax deductable 
Its a battle and I cant see a solution to the problem without more police allocated to it and a few good sting operations set up to catch a few. Once it starts getting more risky they will move onto something else.
When I did site management, we used to have motion sensors and silent alarms dotted around site. They would be monitored by a company who would call the nearest security firm as a response or if several alarms were triggered, the police would get a call. I had several occasions where I was last man on site in the dark and locking up the site office, felt like I was being watched - you know you get that feeling sometimes? Well sure enough, not 5 mins after I had locked the gate, the security company were calling me "are you still on site?" NO but I thought someone else was there with me - get down there! I didn't go back, it wasn't in my pay grade to fight what could be a gang of travellers on my own. Now with my own kit, I'd at least try and scare them off but the reality is they have much less to loose than you do and the law just isn't in your favour.
Anyway the security and police turned up within 10 minutes, didn't find anyone but cabs of machines had been opened and the site office had been attempted to be opened up with scaffold poles. Good job I use all 3 locks on the door, they should of seen that when they were watching me lock up
Saw that myself. As you say, a few motion sensors inside would have been a good idea although I wonder if coming through wall where telephone cable was, was in order to over ride / cancel an alarm
.... ..... ... ... big enough to break an arm, but still throw-able if you wanted to stop a runner ...... a few of 'em got to see some action over the years .... was very dark going in there, at the dead of night, on yer own, sometimes