Topside chunks still tough after 2 hours cooking?
Topside is a good cut of beef for slowly braising, which is what you're doing here. I assume you're following a recipe that calls for 2 hours of cooking? Many recipes for braised meat dishes tend to understate the amount of time it needs to be cooked to become tender (just like how they will tell you you can caramelise onions in 20 minutes). 2 hours is a very short time for this kind of dish. I tend to cook braised beef for anywhere between 4 and 6 hours to get it tender enough to fall apart. It takes time for the chemical reactions that you're after to take place. Give it at least another two hours, and it will be much better.