yup .... wrong saddle and not in the correct position may seem fine for 30 miles or so, but after that, you will be standing and pedalling all the way home ....
a decent leather saddle takes a while to break in, but don't go on a 100 mile ride as soon as you get it ... do short rides until your sit bones break it in ... some say it can take up to 500 miles to get comfy ....
I have an Gilles Berthout Aravis saddle that was/is comfy straight out of the box .... took 2 short rides to adjust the position and since then, I don't even think about the saddle when I ride
another one that is highly regarded by many that ride long distance and which is on my 'wish list' (but which I have not tried yet) is the Sella Anatomica x-series:
I was talking to someone a few weeks ago about the Selle Anatomica. He had an old Brooks with a cutout, and said that Selle Anatomica had initially modified Brooks saddles (which surely are available in the UK even if made in China).
I'm seeing this Brooks B17 with a cutout.
Amazon.com : Brooks Saddles Imperial B17 Standard Bicycle Saddle with Hole and Laces (Men's, Black) : Bike Saddles And Seats : Sports & Outdoors
I'm not finding much info on that saddle. Seller lists name as "Brooks England", but it doesn't necessarily have to be the Brooks company.
Brooks saddles are supposed to get more comfortable when broken in. I assume that is true of all thick leather saddles.