Fewer ads for flagship radio station.
The move at Capital FM comes in a bid to win back listeners whose dwindling presence has hit first-half profits.
GCap will also combine and rebrand its analogue Capital Gold radio services - including its Birmingham-based operation - with the national digital station Life.
It also plans to sell off nine further stations, none of which are in the Midlands.
The group revealed yesterday that its key London station Capital FM would never play more than two advertisements in a row as part of a "groundbreaking policy" aimed at halving the amount of time spent on commercials during the day.
The company was responding to listener feedback after the station's audience figures fell to 1.8 million from 2.9 million in 2001.
And GCap said: "Our plans for Capital FM represent the first steps in our plans for revitalising the network's key stations including BRMB."
A spokeswoman said there were no specific plans on the table for BRMB but the policy of reducing the number of ads would be considered once the performance at Capital FM had been assessed.
GCap shares slumped 18 per cent after it said it did not plan price rises to compensate for the reduction in advertising, meaning that revenues from the station were likely to be pounds 7 million lower than a year earlier.
It also warned of continued tough advertising conditions, with revenues down five per cent in November.
The figure was 11 per cent lower in the six months to September 30, a period when profits fell to pounds 12.4 million from pounds 17.3 million a year ago.
Chief executive Ralph Bernard described the results as "extremely disappointing" and said management planned firm action following a root-and-branch review.
As well as reviving the performance of Capital, GCap pledged to concentrate its resources on "commercially attractive" regions where it can attract listeners from the BBC.
It will expand its Xfm network through the rebranding of Beat106 in Scotland and digital station The Storm, while it intends to combine Capital Gold with GCap's national digital station Life.
Nine analogue stations will be sold.
GCap said it planned to introduce the new advertising policy at Capital on December 12, followed by a re-launch of the station on January 3.
Mr Bernard said: "We intend to bring listeners back to Capital FM by giving them the kind of radio station that they have told us they want.
"A key area of listener feedback has been around the number and frequency of commercial messages."
GCap has also undertaken major research into the type of music listeners want played on Capital