Had Mr Nowab been drinking, that kind of affects it massively. One read is solid tricky player, other is 1 hand glass of wine other hand shovel the chips in.
With stack sizes i'd prob want to raise something small ~185, kinda depends because he's alot more happy to put it in himself than he is to call it off.
He could well have Overs/gutshot or just a delayed cbet, possibly TT/JJ.
If you flat turn and river is non club, K or Q then we're mentally golden but he may not have much of a hand to pay us off with; if you raise turn and he folds out his whiffed hands, calls his more marginal holdings and jams his combo-ish draws then we're obviously getting value on the turn. Once the river hits though if the turn has gone bet call we could be put in some really icky spots with stack sizes on clubs or a K/Q if he just leads out/open jams into us.
If you flat the £75, and the pot goes heads up, there will be £255 in there and you will get another £150 or so out of him if he value bets worse or bluffs, or check-calls worse on the river. It would be really strange if he check-raised the river once you have flatted turn, so I wouldn't be worried about that.
What makes my brain hurt about this hand is that you can get your £150 of value on pretty much any river card, given that you have flatted the turn and under-repped your hand. You want to raise turn to protect your hand and build the pot, BUT then at least one-third of the deck will either kill your hand or kill your value on the river, if he even calls your raise.
What about the two players behind? I guess you could stay on the down-low with one player left to act, but two? You could invite them into the pot but you will have to fold some rivers. You could come out of the closet and make it £175 with £300 behind. Urggghhhhhhh but then Simon Nowab is good enough to fold his top pairs/over pairs and call with his draws, and you lose value from all the crappy hands behind you that would flat Simon's £75.
You could shove and be happy with the £180. But you have a set. You make more than £180 when the river comes a safe card, but you could lose a chunk if it comes A, K, Q, 9, 8 or club, especially in a multi-way pot. Thats half the deck.