Miller joined the c-store and CTN giant in the new role of buying director on Monday following the sudden departure of Start. The company declined to comment on the reasons for Start's exit.
Miller's most recent post was as Spar's trading director, a role he held from 2003 until last year. In that position he consolidated his reputation as a hard negotiator and sharp trader and turned around Spar's own-label range.
"He's an experienced and competent guy. He did a good job at Spar and I would expect him to do a good job at Martin McColl," said one industry source.
Miller joins McColl at a challenging time for CTNs. The newstrade is in decline and is struggling with rising carriage charges and the fact that single-price and general discounters are gunning for a bigger share of the confectionery market.
"It's difficult within the key CTN areas to make big price adjustments so I think what Peter will have to do is more about blending in opportunities, whether products or services," said the source.
Start played a key role in the creation of Martin McColl when, as TM Retail, the company was subject to a management buyout.
Martin McColl is second in The Grocer's Top 50 ranking of independent grocery retailers and is the UK's largest independent c-store and CTN chain. It posted a 2.2% hike in full year sales to £771m but pre-tax profits slumped 77.3% to £4.9m after it sold 41 of its hospital stores.