I watched Supershoppers. I can't find the episode, but as far as I can remember, the facts are this...
It costs a lot more to use liquid hand soap. A bar of soap can last 400 times longer than a bottle of liquid hand soap, does the same job (even the antibacterial ones) and is considerably cheaper.
I've not long bought fancy dispensers for hand soap. Okay, they were extremely inexpensive liquid dispensers, but were a considerable cut above re-using the old plastic bottles of previous purchases.
I don't use the normal liquid soaps, I use bubble bath. I can pick up a litre bottle of reasonably okay stuff for 85p. The basics soap is 25p for a bar that will last a considerable time but I would have to find a place for it to fit on the tiny cloakroom handbasin that was all that would fit in our bathroom and then clean off the gunky sludge that bar soap can leave.
I also have a nine year old son. Nine year old boys do dreadful things to handbasins as it is. I know that one of my duties would now include scraping dirt off the soap.
I think I will continue to be extravagant and use the liquid soap for now.