Hi Aspin
I've found the marriage I think for Alexander Jnr and Jane McKay Gordon on IGI, actual extract from the OPRs:
ALEXANDER MCKENZIE Marriages: Spouse: MCKAY GORDON
Marriage: 10 JAN 1834 Loth, Sutherland, Scotland
This also looks like the birth of their first daughter Ann:
ANN MC KENZIE Birth: 06 NOV 1834 Loth, Sutherland, Scotland
Parents: Father: ALEXANDER MC KENZIE Mother: MC_KAY GORDON
And these are some of their children:
1. JAMES MC KENZIE Birth: 26 NOV 1836 Loth, Sutherland, Scotland
2. ISOBELLA MAC KENZIE Birth: 08 MAY 1842 Loth, Sutherland, Scotland
3. ANN MC KENZIE Birth: 06 NOV 1834 Loth, Sutherland, Scotland
4. MARGARET MC KENZIE Birth: 30 OCT 1838 Loth, Sutherland, Scotland
5. MINA MC KENZIE Birth: 26 JAN 1845 Loth, Sutherland, Scotland
6. JANET MC KENZIE Christening: 21 OCT 1840 Loth, Sutherland, Scotland
There are a couple of birth entries in Loth where only the father's details are given. I wondered if this could be relevant:
ALEXANDER MACKENZIE Birth: 25 APR 1811 Loth, Sutherland, Scotland
Parents: Father: ALEXR. MACKENZIE
Other siblings perhaps with only father Alexander MacKenzie showing:
1. JAMES MC KENZIE Birth: 21 OCT 1808 Loth, Sutherland, Scotland
2. ROBERTA MC KENZIE Birth: 29 JAN 1816 Loth, Sutherland, Scotland
7. FLORA MC KENZIE Birth: 04 OCT 1806 Loth, Sutherland, Scotland
The earliest parish register details I can see for Loth on IGI start in 1795 for Births and 1809 for Marriages. If we have the right family above, it may be one of the potential reasons why Alexander Snr and Ann Polson's marriage doesn't show.
Regards.
Monica