Bear in mind that what may appear to be discrete dating sites e.g. Capital FM are actually run by companies which have other dating sites in their stable. Capital FM's is owned by Dating Lab, a Jersey registered company which runs sites for Global Radio (which is Capital, LBC, Heart and others and other media brands e.g. The Times, The Telegraph and Saga.
This may mean that though you register with, say, Capital FM, your profile may also be seen by people who register with dating sites run by those other brands. You'd need to check the small print.
It's can be a good thing in that your profile will be seen more widely but also means that it is being seen by people who don't necessarily share your interest(s) e.g. classical music, or your world view if that is important to you.
For example, Match group own more than 45 brands as well as Match including Tinder, PlentyOfFish and OurTime.