For their children, the following Clarke births with a Pearson mother have been found:

Name: Mother's Maiden Surname:

CLARKE, EMMA     PEARSON  
GRO Reference: 1868  J Quarter in WOLVERHAMPTON  Volume 06B  Page 608
CLARKE, HARRIET  NEVILLE   PEARSON  
GRO Reference: 1867  S Quarter in NORTHWICH  Volume 08A  Page 225
CLARKE, LUCY     PEARSON  
GRO Reference: 1866  J Quarter in WOLVERHAMPTON  Volume 06B  Page 569
CLARKE, MARY  ANN   PEARSON  
GRO Reference: 1867  D Quarter in HAMPSTEAD  Volume 01A  Page 565

CLARKE, GEORGE     PEARSON  
GRO Reference: 1865  J Quarter in SHOREDITCH  Volume 01C  Page 119
CLARKE, THOMAS  PEARSON   PEARSON  
GRO Reference: 1868  J Quarter in NORTHAMPTON  Volume 03B  Page 90
CLARKE, WILLIAM     PEARSON  
GRO Reference: 1867  S Quarter in ALTRINCHAM UNION  Volume 08A  Page 159

CLARKE, ARTHUR     PEARSON  
GRO Reference: 1873  J Quarter in MILE END OLD TOWN  Volume 01C  Page 486
CLARKE, FRANK  WILLIAM   PEARSON  
GRO Reference: 1873  D Quarter in THETFORD UNION  Volume 04B  Page 359
CLARKE, FREDERICK     PEARSON  
GRO Reference: 1869  D Quarter in LAMBETH  Volume 01D  Page 359
CLARKE, HARRY     PEARSON  
GRO Reference: 1873  M Quarter in CHORLTON  Volume 08C  Page 790
CLARKE, HENRY     PEARSON  
GRO Reference: 1871  J Quarter in LAMBETH  Volume 01D  Page 358
CLARKE, WALTER     PEARSON  
GRO Reference: 1872  M Quarter in WARRINGTON  Volume 08C  Page 185

CLARKE, ALICE  MAUDE   PEARSON  
GRO Reference: 1869  J Quarter in SHOREDITCH  Volume 01C  Page 96
CLARKE, EDITH  MARY   PEARSON  
GRO Reference: 1870  M Quarter in THETFORD UNION  Volume 04B  Page 425
CLARKE, EMMA  JANES   PEARSON  
GRO Reference: 1872  J Quarter in THETFORD UNION  Volume 04B  Page 401
CLARKE, HANNAH     PEARSON  
GRO Reference: 1873  M Quarter in WOLVERHAMPTON  Volume 06B  Page 663
CLARKE, MARIA     PEARSON  
GRO Reference: 1870  M Quarter in ALTRINCHAM UNION  Volume 08A  Page 161
CLARKE, MARION  SARAH NEVILLE PEARSON  
GRO Reference: 1870  M Quarter in NORTHWICH  Volume 08A  Page 231
CLARKE, MARY  ELIZABETH   PEARSON  
GRO Reference: 1871  M Quarter in CHORLTON  Volume 08C  Page 771

CLARKE, MARY  ALICE   PEARSON  
GRO Reference: 1876  D Quarter in BARTON UPON IRWELL  Volume 08C  Page 627

CLARKE, ALFRED     PEARSON  
GRO Reference: 1875  M Quarter in CHORLTON  Volume 08C  Page 826
CLARKE, ARTHUR     PEARSON  
GRO Reference: 1874  J Quarter in COVENTRY  Volume 06D  Page 504
CLARKE, JOHN  HENRY   PEARSON  
GRO Reference: 1876  M Quarter in STOCKPORT  Volume 08A  Page 49
CLARKE, JOHN  JASPER   PEARSON  
GRO Reference: 1878  D Quarter in CHORLTON  Volume 08C  Page 352
CLARKE, REGINALD  RAY   PEARSON  
GRO Reference: 1875  D Quarter in THETFORD UNION  Volume 04B  Page 373
CLARKE, WILLIAM     PEARSON  
GRO Reference: 1878  D Quarter in STOCKPORT  Volume 08A  Page 42

Of these Harriet Neville and Marion Sarah Neville are known to have been their children as they appeared in the 1911 census in Ireland with their eidowed mother.

And there is no Marshal F Clarke who has been told to me as the grandfather of the above Antony Mount, so there is a possibility that Marshall Neveill and Mary Elizabeth Clarke moved out of the country after their early children were born.  And if so, any further reocrds will be difficult to find.
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There are rather a lot of Marshall Neville, Marshal N and M.N. Clarke records which may be one, or more, people:

1827: Walcot, Somerset baptism of Marshal neville to Charles and Sarah Osway Clarke.  B. 14 Jul 1827. Bapt 3 Sep 1827.

1858: Law directory of Post Office directory and calendar: Marshal N Clarke was a barrister on the Leinster bar.

1868: In Thom's Irish Almanac as living in 11 FitzWilliam Sq. East, Dublin: Marshall Neville Clarke, barrister.  Also entered there for 1880 and 1884.

1884: Cashel, Tipperary, Ireland: death of Marshall Neville Clarke, but aged 54 so born in 1830.
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In Alumni Dublinenses there is this entry on p. 154:

CLARKE, MARSHALL NEVILLE, S.C. (Mr Browne), Oct 11 1844, aged 18, s. of Charles, Generosus; b. England.  B.A. AEst 1848.  M.A. Vern. 1858.

This makes his birth to be about 1826-7 and corresponds with the Walcot, Somerest record above.

No Marshal Clarke in Alumni Oxonienses nor in Akumni Cantabrienses.
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Their marriage index:

First name(s) MARSHAL NEVILLE
Last name CLARKE
Marriage quarter 3
Marriage year 1864
MarriageFinder ™ MARSHAL NEVILLE CLARKE married one of these people
Mary Elizabeth Pearson, Caroline Eliza Clarke
District Cheltenham
District number -
County Gloucestershire
Country England
Volume 6A
Page number 667
Record set England & Wales Marriages 1837-2005
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