The seven-year-old carried the colours of the legendary three-time Grand National hero Red Rum to three victories over hurdles last term, completing her hat-trick with a Listed success at Doncaster in March.
She has not been seen in competitive action since, but is closing in on a comeback and is being readied for her chasing debut.
McCain said: "She schooled on Friday morning and Will (Kennedy) was in, we gave her another pop over fences.
"She is in good form and will be running in the next three weeks, subject to the ground coming. She is very ground dependent.
"We made a couple of entries at the festivals in the spring, but the ground didn't come.
"She was always going to be more of a chaser than a hurdler.
"I may start her over a two-and-a-half (miles) somewhere if the ground is there, just to get her going, but she will want all of three miles."
Lastbutnotleast was the last horse bought by the late Ginger McCain, Donald's father, before he died in in 2011.