Nelson Peltz has once again emerged as a key power player in the fortunes of Kraft and Cadbury after this week’s “astonishing” decision to split Kraft Inc’s $49bn business in two.

Kraft announced plans on Thursday to create two independent publicly traded companies: a high-growth global snacks business including Cadbury, Oreo, Ritz and Tang, with estimated sales of $32bn; and a high-margin North American grocery business with estimated sales of $16bn. A more focused approach would unlock greater shareholder value as “investors would be able to value the two companies based on their particular operational and financial characteristics”, it explained in a statement.

But while reports attributed the new strategy to Kraft advisors Centerview Partners, Evercore Partners and Goldman Sachs and another legendary investor, Warren Buffett, this week told CNBC he had given his blessing to the proposed split when he met with Kraft CEO Irene Rosenfeld on Tuesday a City source said the return of Peltz to the Kraft share register during Kraft’s first quarter was intriguing. “If he hasn’t had a direct bearing on this about-turn, it’s an amazing coincidence,” he said.

The activist investor bought 12.2 million shares in Kraft Foods during its first quarter, worth almost $500m. And his return to the share register followed a controversial move by Peltz in 2007 in which he secured a two-year deal with Kraft management not to publicly criticise the company in exchange for two independent director appointments on Kraft’s board.

When this gagging deal expired part-way through Kraft’s hostile takeover bid for Cadbury, Peltz remained quiet, but by this time he had sold the vast majority of his $1bn stake in Kraft.

It was also Peltz whose outspoken criticism of Cadbury-Schweppes led to its demerger in 2007 a move that ultimately made Kraft’s acquisition of the smaller plc possible.

Former Cadbury chief strategy officer Mark Reckitt described the split as making sense strategically. But he added:

“What’s astonishing is that when Kraft bought Cadbury, this focus was never on the agenda. We said value comes from focus. Kraft believed that value came from scale.

“If Kraft had pursued this focused global strategy when it acquired Cadbury, it could have retained all that was great about Cadbury, using its focus while strengthened by Oreo and the chocolate businesses in Europe and Latin America to mobilise resources for growth more effectively.”

The demerger also leaves Kraft’s Philadelphia and coffee businesses “stranded”, the City source added.