I have 1821 and 1831 Marylebone. Indexed from the original held in Westminster Archives ..... the focus of the 1801-1831 was statistical, the beginnings of serious planning ..
BUT the Marylebone Index only shows Head's name and address - other stats not indexed apparently included occupation, and counts of household members etc.
Here are the 1821 Mc's section - no sign of your McGarricks, sadly not MAC either.
MAYS Portland Street Great Page 288
McADAMS Queen Street E. R. Page 310
McCLARY Adams Street Bryant Square Page 2
McCULLOCK King Street West Page 184
McDIARMID Berkley Street Upper Page 26
McDONALD Berkley Street Upper Page 26
McDONALD Castle Street East Page 55
McDONALD Gloucester Place Portman Square Page 141
McDONALD Rebecca Court Page 315
McDONALD Rebecca Court Page 316
McDONALD Spring Street Page 338
McDONNELL Orchard Street Page 255
McDONNELL Queen Charlotte Row Page 309
McDUFF CharlesStreet P.Place Page 69
McFARLANE Cumberland Place Great Page 93
McFARLANE Cumberland Place Great North Page 94
McGAREB Harley Street Page 154
McGOWEN Newman Street Page 234
McGREGOR Cirencester Place Page 79
McGUIRE High Street Page 161
McHUGH Marylebone Lane Page 203
McINTOSH High Street Page 164
McINTOSH Park Place Page 273
McINTYRE Beaumont Street Page 20
McKARDY Dorset Street Page 107
McKAY Ogle Mews Page 251
McKENNA Cato Street Page 59
McKENZIE East Street Page 114
McKENZIE Portland Place Page 281
McLANDISH Charlton Street Upper Page 74
McLANDLISH Charlton Street Upper Page 74
McLEAN Adam and Eve Court Page 1
McLEAN Queen Street E. R. Page 310
McMAHON York Street York Place Page 389
McMILLAN Moor Street Page 224
McMULLAN St John`s Place Page 319
McPHERSON Oxford Street Page 264
McQUEEN Edward`s Place Page 124
McQUEEN King Street West Page 184
McQUEEN Newman Street Page 234
MEAD King Street West Page 184
(the meaning of the Initials at the end of some of the Street names - they are the larger streets nearby)
I also looked in 1831 with no success.