Quite possibly he did, yes. But her father arriving on the Windrush is a different story to her herself arriving on the Windrush (she didn't).
Mistake/false memoryon her part? Misinterpretation by - cough - some people of what she actually said? More likely than downright lies being involved...
Only slight snag is that the Windrush was taken out of service, and then destroyed by fire, six years before the eleven year old Floella arrived in the UK. Difficult one to get round, that.............