I am not entirely convinced that Robert is her son either, but there is some evidence to support that claim. When Henry VIII discovered Margaret and Thomas' engagement, he had them both committed to the Tower sometime in 1536. However, Margaret Douglas was later sent to Syon House due to an "illness" and was released in late October of 1537. This "illness" could have truly been a pregnancy, and Henry VIII had her moved there to keep it a secret. Again, I'm not completely convinced either, but there is some evidence to suggest she did have a child with Thomas Howard. I don't know if there's any evidence to support the claim that Robert Howard is that child, though.
Linking some of the relevant profiles so we can get their managers involved in the discussion:
Lord Thomas Howard
Sir Robert Howard, Kt.
Matthew Howard, immigrant to Virginia
My opinion of James E. Moss's Providence Ye Lost Towne at Severn is that he linked the ancestry of Matthew Howard of Maryland to Lord Thomas Howard by heresay. He provides no concrete historical proof of what he
writes about. Where is it proclaimed that James I recognized his descendants? I have yet to talk to a qualified historian who believes that Robert Howard was the son of Lady Margaret Douglas and Lord Thomas Howard. Until proven otherwise, it is all rubbish. Amen.
My apologies for not replying earlier..I have removed the parents for Sir Robert Howard, Kt. and added some notes to the profile..