Dame Helen Branch, a 16th-century nonagenarian

Probably a long shot, but I'm on the trail of Dame Helen Branch (or possibly Helena/Helenae) who died - in her nineties - on 10 April 1594 and was buried in St Mary Abchurch in London.

A pamphlet was published containing a poem celebrating her virtues. (Infuriatingly short on detail, as such things usually are.) It is titled A Commemoration of the life and death of the Right worshipfull and vertuous Lady Dame Helen Branch, late wife to the Right Worshipfull Knight Sir John Branch, sometime Lord Maior of the famous Cittie of London, &c. and can even be found on the web here.

It is curious that the poem seems to be widely attributed; to Joshua Sylvester, and to John Phillip[s], also here.

Yet the original pamphlet, which I was holding in my hands today, has a closing signature "W. Har." - and it is hard to see how you can get either of those names from that. The ODNB says it was written by a William Herbart or Herbert, but not the most famous one of those?! Another source says it was a Sir William Harvey.

Her second husband, Sir John Branch, a draper, was mayor 1580-81.

Her first husband had been a John Mynors, who may have been (if he was a fair bit older than her) the John Mynors who in Lincolns Inn in the Trinity Term of 1494 was, with William Fyllyff and Richard Eryington, fined "for not keeping or preparing the moots for two days as they ought, when divers Benchers were prepared to hear the moots". (These were formal disputations.) He may have some connection with a composer, William Bryd.

Her father was William Nicolson, her mother Joan.

In the back of the pamphlet is what looks to me like contemporary handwriting recording what seems to have been the epitaph on her tomb, mostly in Latin, but with a bit of English. There's mentioned in that a Robin? Nicolson, also "JOHANNIS DIINORS" and "CVIBERTI BVCKLE".

I'd be eternally grateful to anyone who can shed any more light on her life; if I get time tomorrow I'll probably try to transcibe the handwritten bits in the pamphlet (although working from handwritten Latin IS a challenge.) I'd also welcome any suggestions for other directions of research; I've got a few threads, but they are pretty thin.