Quidco took 8 months to pay my £45 SPG Amex referral money from last August. Did get it in the end, to be fair, even though the card had been cancelled for 4 months by the time I got it!!

This is not a bad deal, although the SPG Amex is currently offering 20k Starpoints (25k BA) for signing up, with some - less - Quidco and so also worth a look. And of course the BMI MBNA Amex is 20k Avios with a very modest income requirement, so better for those who don't earn the £20k Amex want.