Hi Viv,
I've just realised that it looks as though you have left out a generation? (You didn't put dates.)
You wrote:
"Ewan and Margaret Howland's daughter Margaret married James Bell.
Their daughter Frances Sarah Bell married Robert Shimmin
Daughter Margaret Shimmin married James Alfred Kewley and they were my grandparents."

I have Margaret JOUGHIN bapt.10 March 1737 daughter of William Joughan & Joney Dougherdy, married Ewan HOWLAND of KK Bride 3 Aug.1771 in Andreas. Children bapt. Andreas: Margaret Howland 17 May 1772; William Howland 2 Mar.1774; Joney Howland 17 Sept.1775; Isabel Howland 20 Sept. 1783.

Then, if this was the right family, I think you missed out William Howland (b.1774) married Margaret Garret 29 Dec.1821 Andreas?
Their children's bapts from IGI: MARY ANN HOWLAND 15 JUN 1828 Andreas, JOHN HOWLAND 6 JUN 1824 Andreas, HUGH HOWLAND 26 JUN 1831 Andreas, MARGT. HOWLAND 17 JAN 1822 Andreas.

And that it was this Margt, daur of William Howland, who married James Bell 18 MAY 1851 Braddan? [IGI] (Not Margt b.1772.)
James Bell bapt 07 JAN 1822 Kirk Michael, Father: SIMON BELL, Mother: JANE CLAGUE. [IGI]

In Douglas in 1871 census both aged 28, James Bell b.Michael.
Burial: BELL, Margaret 51 Bra 26 Mar 1873 [Brian Lawson's website.]

1881 census
James BELL Head W Male 54 Michael, Isle of Man, England Hotel Keeper Robert SHIMMIN Son In Law M Male 30 Foxdale, Isle of Man, England Farmer Frances S. SHIMMIN Daur M Female 28 Ramsey, Isle of Man, England Stanley B. SHIMMIN Grand Son Male 10 Douglas, Isle of Man, England Scholar Frances E. SHIMMIN Grand Daur Female 8 Douglas, Isle of Man, England Scholar Thomas A. SHIMMIN Grand Son Male 4 Douglas, Isle of Man, England Margaret J. SHIMMIN Grand Daur Female 2 Douglas.

Hope I've got this right? If so, could you please give the details from the 1851 Braddan marriage to confirm the correct fathers and their occupations, and also the details from William Howland's Andreas marriage to Margaret Garret 29 Dec.1821 to see whether he was a widower, because he would have been about 47 if the right William?

Thanks,

Sue