Pieter van der Merwe, Greenwich Curator Emeritus, has recently added: ‘I'm sure it’s one of the John Cleveleys (rather than attributed to). The problem is the relative lack of oils by the Younger. It’s more like his composition - from the one or two that aren't themselves questionable as 'after' - but the manner is otherwise very like his father - perhaps unsurprisingly. He's mainly a watercolourist despite the fact he did do oils.’

The low horizon suggests the influence of the Dutch Marine style of the 17th Century. If this painting is by either Cleverley I'd suggest the Younger.
The Younger's style is more atmospheric and less formal than that of his father or say Francis Holman, a painter from the same period and of known Thames subjects. The East Indiaman (?) to my eyes, is a tad short
I think we can discount Robert Cleverley his brother on stylistic grounds.

It is very similar to this:

https://bit.ly/3oKPmy7

An older discussion.

Yes, those works are very similar, Jacinto. The location is even the same - Deptford. My first attachment is a composite that includes “Launching at Deptford”.

I’ve been comparing the work “The Naval Dockyard, Deptford, London” (rigging, flags, sails, small boat) to one by John Cleveley the elder at the National Maritime Museum dated 1752 and I think they are very similar. If the mystery work is about the same age, it would more likely be by John Cleveley the elder.

“A Naval Brigantine in a Calm Sea”
https://tinyurl.com/5epdez3z

Two composites are attached (I used the second image at this link https://tinyurl.com/uxbsrsb5).

This picture is currently in store and I'll try and fix an opportunity to see it. I'll also have a word with an NMM 'ships' colleague about its 'Naval Brigantine in a Calm Sea', not because of the attribution but the title: the Navy would probably have called it a 'sloop' in terms of its officlal 'rate' but the rig is really that of a brig with a lateen yard rather than a gaff on the mizzen -which is unusual in painting terms for vessels of the size, though otherwise common in pre-1750s shipping.

I don't suppose you've been able to see this work, Pieter? Then perhaps the discussion will be ready for closure.

Sorry: this has rather slipped my mind, let alone Covid obstructions in the interim. If Marion could supply a higher definition image it might help though the one on the collection website is a bit better and provides another clue which is the size of the trees in front of the Master Shipwright's house. This is the building with a Dutch bell-gable end immediately astern of the Dockyard sheer-hulk, lying on the left, and you can just see one of two trees between it and the river wall.

The earliest date on a Cleveley the Elder oil is still (I think) 1747 and
Teddy Archibald pointed out long ago that the sequence if not exact date of his Deptford views - painted over about 30 years - can be judged by the comparative size of these trees from one picture to another and. Here they are still quite small, which reinforces my view that this is 'Elder' rather than 'Younger'.

The latter was born on 24 December 1747 and by the time he could have painted at this sort of level - say about 20-25 at earliest (c.1768-73) - the lateen mizzen yard seen on the ship at centre (a 6th-rate 'sloop' as the Navy would have called it based on size) had also gone out of use and been replaced by a gaff at the head of the fore-and-after 'driver' or 'spanker' sail and a boom at the foot, both hinged directly to the mast. This was a change that started in the 1750s/60s in small ships and spread to large ones over about 30-plus years.

In other words this looks like something by the Elder from the 1750s or and given it is only at present 'attributed to' the Younger I'm happy to recommend 'attributed to' the Elder instead, at least until I can see it: I think that's a safer bet.

The church at left is St Paul's, Deptford, designed by Thomas Archer and completed in 1730, so it was still a relatively new landmark for inclusion in something painted in the mid century. (It was also where Clevely and other of his family were buried.)

I

The title could also improve as the subject is really the ship in the foreground. It might have been painted for the captain (since in commission with his pennant flying at the main) if that is the figure showing it off to a lady visitor -perhaps his wife - at the poop rail.
There are 16 broadside guns (8 x 2) suggesting its a sloop of about 20 including chasers fore and aft so an alternative titlewould be

'A Royal Naval sloop moored off the Royal Dockyard, Deptford'

The sheer-hulk to left is the one attached to the dockyard for masting and de-masting. Between the now-vanished Great Storehouse (except for the clock turret, which is now on top of a modern brick tower at Thamesmead) and the Master Shipwight's house, which survives, one can see two ships in the double dry-dock (i.e. double length): a first- or second-rate three-decker at the landward end and (probably) a frigate behind it.