Beef topside roast - help!

[TweetPetite]

I've saved up and bought a 2.185kg (to be precise!) joint of beef topside rather than the rib joint I've bought in the past. (Only bought rib once sadly as so Expensive it can't be repeated! I need to feed 8!)
How long to cook for? We love it rare- medium rare. Have googled but there's a HUGE difference between timings. Has anyone succeeded with this cot? Puhleeeeese help!

Oops 'cut' not cot.

I think it's 20 mins per pound plus twenty minutes, so 2.185 is about 4.8 lbs and would take 116 minutes. So nearly two hours. Don't forget though that beef keeps cooking inside after you've taken it out if the oven, so I always knock 20 mins off so it's not too overdone. Put it in for an hour and a half on about 190?c and see how it goes.

Will that be enough to feed 8? I only get slightly smaller for just me and dd (8) lol we do have leftovers obv but not huge amount.

We like ours rare and cook a 2kg rib of beef for no more than 1 hour 15 mins max.
Topside I cook the same but definatley a lot tougher than rib of beef.

I want beef now lol

We had a 1.3kg piece of topside on Sunday. We marinaded overnight an cooked for 3/4hr at 170fan, it was lovely, rare and tender. 15mins per 500g for rare, 20mins per 500g for medium. Then rest for at least 30mins.

Soooo sorry for not returning to thank you all. It's so rude when the OP doesn't return, so apologies. It was quiveringly rare and delicious - thanks for the advice. 15 mins per lb was perfect plus extra 20 in the end. I'll definitely buy again. Thanks again.