Trainer Paul Nicholls had saddled nine previous winners of the recognised Gold Cup trial, with Ditcheat greats Kauto Star (2007) and Denman himself (2008) both claiming victory en route to Cheltenham glory the following month.
Dual King George hero Clan Des Obeaux, who won a rescheduled running of the Denman Chase at Ascot two years ago, was the 6-5 favourite to get back on the winning trail, having finished third when bidding for a hat-trick in Kempton's Boxing Day showpiece on his latest outing.
However, just as he did in the King George when Frodon claimed the prize, the nine-year-old had to make do with minor honours as a lesser-fancied stable companion made every yard of the running under Bryony Frost.
Secret Investor was a 14-1 shot, but jumped and travelled with zest to keep the pressure on the chasing pack.
Clan Des Obeaux loomed up looking a big threat under Harry Cobden, but Frost's mount refused to bend on the run-in and after a titanic tussle, it was Secret Investor who found most for pressure to win the day by a neck.
While the race is viewed as a Cheltenham trial, Aintree was uppermost in Nicholls' mind after the race.
He said: "I couldn't see that happening, but having said that, he ran well in it last year and just kept galloping.
"I wouldn't be surprised if both head now to Aintree for the Bowl.
"I told Bryony to ride him from the front because we wanted a good pace for Clan, but Harry said his horse was just carrying his head a bit high, which leads me to think we should put cheekpieces on him next time.
"It's something we've considered to sharpen his mind and we gave him the benefit of the doubt until today."
Aintree is also on the agenda for Nicholls' Ascot Chase runner-up Master Tommytucker, although plans are undecided for stablemate Cyrname who was pulled up in the same race.
He said: "Master Tommytucker has some out of Ascot very well and will now go for the Melling Chase at Aintree, but with Cyrname he just can't breathe and we'll have to see with him."
There was a sad postscript to the Denman Chase as the David Bridgwater-trained The Conditional suffered a fatal injury, with Nicholls expressing his condolences.
He added: "I was very sorry to see Bridgy lose his stable star just now and we all feel for him."