Why did my roast beef turn out like literal card board please

[RoasBeefCardboard]

Topside with a layer of fat, I did it on 200 for 15 mins, I also browned it.
Then 160 for the rest of the time under foil.

It was hard, like card board and incredibly dry. I don't normally have beef and this was appalling and not cheap either.

Beef seems to go from raw to overdone in a blink of an eye. I have to use a thermometer thing like https://amzn.to/427MIWQ

It’s not blood you can see when there are pink juices either.

It dies sound like you massively overcooked it. That wil inevitably make things dry.

Get a temperature probe. You’ll never look back!

If you're a beginner I would start with brisket. It needs very, very long slow cooking but will be tender and soft with gorgeous gravy. If you have a slow cooker about 8 hours.

@StragglyTinsel we do have one but I've never had to use it..
I wouldn't know how to use it in the beef.

I stick it in when and how and what does it mean?

So, I need rolled rib, temp gage and far less cooking!

@RosemaryDill a very long time ago I did brisket and had it in baguette it was delicious.

. What i specifically want now is a proper beef roast like ye old days.... My df used to do a stunning beef roast, and some friends did one that was gorgeous...

In that case you need a much bigger joint, unfortunately.
And one with both external and internal fat, like rib, and cook it medium rare.
Yes, it will be expensive but you will probably get more than one meal out of it, so cutting the cost per head. (Roast beef sandwiches from a home cooked joint are the best.)
As it is you must have spent quite a bit on the topside joint and it really wasn't worth it.

what kind of meat probe have you got?

The easiest option is one of the ones that you stick into the thickest part of the meat, set the desired temperature (lower than the final temperature because it does cook more as it rests) and then chuck it in the over. Mine has a wire that attaches to the little display (which has a magnet on it so I can stick it to the top of the oven). It beeps when it’s hot enough.

If you’ve just got a probe one that can’t go in the over, you periodically take the meat out, stick the probe into the thickest part of the joint and check the temperature. You can baste it before putting it back in the oven.

It’s a useful thing to have for all meats. Takes the guesswork out.

I let all my roasts rest under foil topped with a clean towel to retain the heat. Rest at least 20 minutes. Temperature for beef before resting needs to be below 60 degrees as it continues to cook whilst resting.

Probe goes in the middle of the joint and you want to take it out of the oven when the temperature is 10-15 degrees Celsius less than your target temperature. The target temps are:
Rare 50C
Medium rare 55C
Medium 60C
Well done 70C

M&S do a decent enough rolled rib joint for approx £24 at the “cheaper” end off the market. I haven’t found anything cheaper that isn’t shoe leather.

I would suggest you buy your meat from the butcher not the supermarket. As beef has increased in price supermarket beef has just got worse and worse. You are looking at sirloin or rib for a guaranteed lovely roast but it is so expensive. Topside, silverside and supermarket 'roasting joint' are better in the slow cooker.