There is,it's a medium pink Hybrid Tea rose,which bears the name "Margaret"and has a moderate fragrance.Trade manuals list it as being available from:
Burrows Roses,
Meadowcroft Cottage,

There is a white floribunda rose called Margaret Merril (some catalogues list it as Margaret Merrill )
It has double flowers

Lady Margaret passion flower, red passion flower

Bourbon rose
Rosa 'Maggie' maggie is nick name for margaret

Noteworthy Characteristics: Bourbon roses usually have fragrant blossoms borne in spring or early summer and often again in fall. They are sometimes grown as climbers up a wall, arch, or trellis. They are ideal for borders or hedges, and make excellent companions to herbaceous perennials.

Astilbe chinensis 'Maggie Daley'

Maggie Mott viola

There are sites that give you the opportunity to name a rose for someone, I don't suppose that it will be registered in that name, but who knows? Otherwise the following site gives and alphabetical list of rose names. I have one called Absent Friends and this site also has one called A Faithful Friend. http://www.countrygardenroses.co.uk/products.php?cat=26
Various companies have roses called Margaret.
The other alternative to a plant would consist of doing a Google search and trolling through the results.

Roses - Margaret Merrill (as above) is a good sound variety. There's also a mid-pink Hybrid Tea rose 'Margaret'.

Peony - Princess Margaret

If you want a rose, another nice gesture might be to find one that was bred/introduced in the year of her birth.

Thanks to everyone for the suggestion, very kind of you, will look at all of them.

Your welcome - definitely check out Rosa Maggie bourbon rose - a nice antique red rose.

We have decided to go for the name your rose and called it Peggies Rose and the family are delighted, thanks to every one.
Terry

Will you get one for the garden as well?

Yes this is to go into the gardens out side where Peggy lived.

Congratulations, I'm glad you have this resolved and can finally move forward with your plans. She must have been a remarkable person to have made such an impression.

Yes she was a lovely lady, 94 when she passed away, but still had a very sharp mind.