Okay.  Bear in mind that the following information is not confirmed, it's just me putting 2 & 2 together & hopefully coming up with 4  

Henry & Harriet married 10/4/1833, Horsham.
Their children (extracted IGI entries)
William 2/5/1833  Horsham
ANN  23/8/1835      dittoElizabeth 6/8/1837      ditto
Henry 28/2/1841         ditto
Isaac  23/2/1845     Warnham
Harriet  2/5/1847         ditto
JOHN  30/9/1849         dittoMartha 25/4/1852          ditto
Mary Helen  29/6/1856   ditto
So John Holland that you think is the gent standing at the back of the photo is Ann's (your 2x great grandmother) brother.
William:  1833 - died Q2 1912, Horsham aged 79 (2b 373)
1881 - North St. Portslade (police station)
William Holland  47  b. Horsham  Police Constable
Maragret            31
Lydia dau          19   b. Newhaven
William seemed to have married twice, (1) Lydia Huggett Q3 1860, Lewes (2b 235).  Death of Lydia, Q1 1875 aged 34  Steyning (2b 228)  Marriage (2) Q3 1877, Margaret Mitchell, Steyning (2b 447)  Margaret died Q4 1903 Horsham aged 54 (2b 192)
So William could be a candidate for one of the gents as he would have been about 62 in 1895.
Ann 1835 - possible death Q1 1910 aged 74 Horsham (2b 221)
Married William Wood Q2 1858, Horsham.  Possible candidate for one of the ladies as she would have been 60 in 1895.
Elizabeth 1837 - nothing known
Henry 1841 - possible death Q2 1887 aged 45, Horsham (2b 195)  so not a candidate.
Isaac 1845 - Possible death Q2 1908 Steyning aged 64 (2b 185)
Married Elizabeth Hills Q1 1871, Lewes (2b 181)
1881 in Horsham.  1891 The George Inn, Portslade, Syening.
Possible candidate.  As he seems to live in Portslade & died there he probably made the journey up to Horsham for this event.  My money would be that he's the gent on the right as he looks a little more dapper than the others & running an inn on the fashionable south coast in Victorian times might give him the edge as far as fashions go  

Harriet 1847  Nothing known
John 1849  Possible death Q4 1908  aged 59, Horsham (2b 188)  so he could be in the photo as he would have been 46 in 1895.
Martha 1852  Nothing known
Mary Helen 1856  Nothing known
jane