Independent American label from Chicago: Mainstream Records was founded in the first half of the '60s, by Bob Shad.  It offered varied fare, ranging from Jazz and Blues through Soul to Rock; its catalogue featured artists as diverse as Sarah Vaughan, Lightning Hopkins and Ted Nugent.  In Britain, Mainstream arrived late on the scene. The label was launched here by Pye, but the first single on the label didn't arrive until August of 1973.  It issued some forty-odd albums over here, but only six singles, which were numbered in the MSS-300s.   The first Mainstream single to be issued through Pye was Afrique's 'Soul Makossa', which came out on Pye International (7N-25616; 5/73); it is possible that the missing MSS-301 number in the discography below may have been intended for that record.  Mainstream seems to have expired towards the end of 1976.  It never troubled the Chart compilers in the U.K., but Kevin Johnson's 'Rock And Roll' (MSS-304) was a hit in 1975 when it was picked up by Jonathan King and reissued on his UK Records. Distributed By TS Records. Thanks to Robert Lyons For The Info.

73 Not Traced MAINSTREAM MSS 301
73 Doris Duke Business Deal MAINSTREAM MSS 302
73 Chubukos Witch Doctor Bump MAINSTREAM MSS 303
73 Kevin Johnson ThereŽS Nothing IŽD Rather Do MAINSTREAM MSS 304
74 Sarah Vaughan I Need You (More Than Ever Now) MAINSTREAM MSS 305
74 The Electric Ladies King Kong MAINSTREAM MSS 306
75 Welch Lenny The Minx MAINSTREAM MSS 307