The West Yorkshire club secured Super League top spot with a 45-20 derby win over Wakefield Trinity at a throbbing Wheldon Road.
In all their 91 years, Castleford had never finished in pole position, but Daryl Powell’s side did it in style with a thrilling second half showing. They are now just 80 minutes away from a maiden Grand Final and the chance to win a first league title at Old Trafford on October 7.
Shenton, twice relegated with his hometown club, said: “It’s absolutely amazing. It’s been an awesome week.
“We came here with the sun shining and 40 minutes to kick-off it was already packed out. We knew it’d be a special night.
“We were a bit nervous initially and Wakefield turned up. We knew we were good enough, though, and it was an awesome finish. Now it’s time to celebrate before we concentrate on the next step.
“That’s the first goal done – the League Leaders’ Shield – so now it’s time to regroup and totally focus on Old Trafford.
“The crowd was amazing and now we’re in the history books and very proud.
“This is for all those who stood by us in our ups and downs.”
Castleford are 12 points clear of nearest rivals Leeds Rhinos with four Super 8s games still to play.
Powell, who took over in 2013 and turned the side into one of the most exciting sides in recent history, saw them lead just 18-10 at the break. But they were superb in the second period as Kiwi centre Jake Webster finished with four tries.
Powell said: “So many people have worked so hard.
“The boys have been awesome all year and I’d like to thank everyone here (last night); the support’s incredible and this is for you all. It’s just been an amazing season for us and this is a special night that will live long in the memory.”
He added: “We looked really nervous in the first half, but in the second half we were superb and played like we have all season.
“We’ll chill out for a bit now as the boys deserve that, but then we’ll train reasonably hard next week and then crack on.”