But, without the infomation, how do you know if you should be concerned?
[The on condition rules in Canada are about the same as the UK]
If, as the pilot, you can't tell by the way the engine is running, and the aircraft has a valid C of A, I would not worry about it. If you're renting, it's not on condition, if you co own, you'd know, if you're borrowing a private aircraft, that's between you and the owner. But, I'd tread lightly, you might insult an owner by expressing doubt as to the airworthiness of their aircraft based upon a number.
What would you do if someone told you the engine was 2k beyond TBO anyway? If, as the pilot, you can't tell from how the engine runs, why worry?
To be safe for flight, an engine needs five things: Fuel and Fire where and when you need them. If they are not, you can tell right away. Decent compression is good, but you'll know if you don't have that, it won't develop power. It needs oil pressure, which you can tell right away. And, it should not be making metal, but you'll never know that, unless you check the oil filter.
I bought my 150 with 1750 hours on the engine (1800 hour TBO). I put it on condition, did the required maintenance along the way, which included changing cylinders as needed. I ran it to 3550 hours with no problem. I split the case then because of unknown ferrous metal. The inside of the engine was excellent - the metal had come from a crimped on alternator tin part of no consequence. I'm not unhappy I zero'd it, but it would have run fine for some time to come.
Bear in mind that the manufacturer's TBO times, which form the basis of going on condition. Those TBO numbers are not as well established as one might think. The certification test only requires a 150 hour block test, not a TBO run for certification. My experience has not been to place too much value in them. I have flown sweet over time engines, and scary engines not far out of a poor overhaul.
Whenever I fly a new plane, all my Spidy senses are out there for how it "seems" to me. If the aircraft is otherwise airworthy, and the engine "seems" okay to me, that's all I need. If I'm going to buy the plane, and assume the cost of a possible repair, I'll look deeper. I bought a 182 for a friend, with a 600 hour engine. I did all the logbook prepurchase review, good records. I jumped in, it purred, I flew it home 3500 miles, it purred. I took it out and sold it, as planned from the beginning. The new owner was not entirely happy with it, so he split the case - crack in the crankshaft! Who knew?
Just go and fly and enjoy. Be alert all the time to what the engine is telling you, but don't worry, as long as you have provided the fuel, and it is running smoothly....