I don't know how you're going with this search but I've considered a couple of ways that may provide some info.

Both will require some work (sheer hard slog through records in fact) but could be fruitful

One option is a trawl through the 2NZEF enlistment rolls which are available on microfiche. If the man was an officer that narrows the search a little as the rolls tend to list officers in the first section of each listing. Unfortunately, if he was in the Navy or Air Force and serving in the AG Office, then he won't be on the roll. Or if he was in the Permanent Force AND travelled separately, then he may not appear on the roll.

Another option is to search the NZ Electoral Roll for 1946 (now available on Ancestry) for entries for Lyall/Lyell. The search will cover forenames and surnames. You can do a free online search which will provide the person's name and the electorate in they were registered. If you don't have access to an Ancestry subscription (which will allow you to see the actual Electoral Roll entry), then you'll have to go to a hardcopy or microfiche copy of the Electoral Roll.

I don't know what access you have to a library/research centre with this material but if you want to discuss this in more detail, please contact me on: fishpi29
at yahoo.com
Best wishes
Elli