@vshymanskyy and @Gunner I started with a fresh install of Jessie Lite today. After a couple of hours I was almost up and running when the SD card gave systemd errors on bootup. The card wasn’t failing and I tried for a few hours to fix it but no joy.
Tried a second time but this time decided I would install the filesystem to a USB stick and all seems to be fine. Still need to check out my DS18B20 setup but basic operation is fine.
Guide for USB filesystem is at https://www.raspberrypi.org/forums/viewtopic.php?f=29&t=44177
It looks detailed but it’s not really that bad. @paulv wrote it in 2013 but updated it just a couple of weeks ago.
I made a few notes during the Blynk setup but basically they are as published by @vshymanskyy a few posts back.