Chaserider presumably no relation to the branding which NBC Midland Red used in the 1980s? Looks, from the website, like it's a small local independent company which has re-used the name.
Incidentally the 1980s Chaserider appeared to be entirely single-deck too... though PMT used a mix of single-and double-deckers on the 260. Knowing that First run what used to be PMT, I would imagine the 101 is the successor to the 260 - so the pattern at Stafford re. double-deckers seems much the same as the 1980s!
Chaserider is indeed a resurrection of the old NBC identity (as used by Midland Red North) following the purchase of the former Cannock operations from Arriva by Julian Peddle, owner of D&G Bus and renowned bus industry entrepreneur (who also owns Centrebus and has financial interests in Select Bus and Midland Classic).
The 1980s Chaserider was a name used for the Midland Red North operations at both Cannock and Stafford. Stafford was single deck in the main and guess that does continue now.
However, Cannock definitely had some deckers. They started by having some original Midland Red Fleetlines, with more coming from the purchase of Harper Bros of Heath Hayes. In the mid 1980s, as well as some former London DMSs, Midland Red North bought some brand new ECW Olympians (including some coach seated examples) and these were allocated to Tamworth and Cannock; the Cannock ones were used on the Rugeley to Birmingham expresses and the former Harper Bros 156 Cannock to Birmingham via Brownhills. Those routes no longer exist though in those forms.
IIRC, in the early 2000s, they still had deckers on the 156 (early Arriva route branded) and I certainly experienced deckers (ex London & Country Citybuses) on the 860 Lichfield to Cannock at that time.