This is… pretty recognisable. If it had been captured in, say, the Illustrated London News, even in the background, I think it would be conclusive.
Quote
PUBLIC NOTICE.
COACH & HORSES INN, HILSEA.
MR. JOHN LOVELOCK, of the above-named Inn, having obtained the kind permission of the Government authorities, has erected (for the use of the public on Monday next), a most substantial PLATFORM on the top of his house, close to which all the Volunteers will pass on their way from Southsea Common to Portsdown Hill.
From the platform the public will have a view over a range of 10 miles from Fareham, Portchester, to Bedhampton, as also of all the movements, both of the gun-boats in Portchester Lake and of the troops on the Hill during the Sham Fight.
Tickets to be obtained on the premises, and at the Hampshire Telegraph Office, High-street, Portsmouth,—price 7s. 6d. each.
— Portsmouth Times and Naval Gazette, Saturday 11 April 1868 source