Lorraine added: "Harry admires his big brother and has recently followed William and Kate in doing a great job raising awareness about mental illness, particularly among young people."
The TV host couldn't resist comparing Kate to Harry's long-distance girlfriend, US actress Meghan Markle.
"Times have changed, and being an American divorcée is no longer seen as a heinous sin," Lorraine wrote.
"In 1936 Edward VIII had to abdicate the throne when he married Wallis Simpson, a US citizen who had twice been though the divorce courts."
The columnist also praised Kate, 35, for "quietly making a difference" through her charity efforts and for being an asset to the royal family.
The Duchess, who Lorraine says is "growing in confidence", has gone solo for an increasing number of official events of late as well as high-profile red carpet events.
Earlier this week she carried out charity work in Wales, and on February 12 she made a VIP appearance at the BAFTAs.
"Her freshness and sweet smile made most of the A-list actresses look somewhat overdone, as though they were trying just a bit too hard," wrote Lorraine.