Wrist watches, watches
Beach & PoolHomeDamaged Dressing
A Chorus of Frogs A Chorus of Frogs The morning after Propellant 23
Silent dust Take Over The Wringer Return of the Cybernauts TNA Abgels of Death
Eagle's Nest Cat Amongst the Pigeons Return of the Cybernauts Return of the Cybernauts
John Steed has a nice collection of wrist watches with different watch bands and at least two golden Hunter watches (Dial a Deadly Number and Super Secret Cypher Snatch).

I don't think it's possible to identify the watch brands, because you don't get a close up at the watches. The only exception is The Morning After (second row left), but you can't see a name on the watch.

Nevertheless it is possible to state a few things.
Younger Steed (season 2 and 3) prefers watches with leather bands, uses also Nato Straps and metal bands and most of the time round light dials, a dark dial can be seen in The Removal Men.
Series 5 and six Steed prefered a golden watch with metal watchband, in Return of the Cybernauts he had a watch witch a leather clasp.
Elder TNA Steed prefers a quare golden wristwatch with a fine metalband, but there's a watch with a black leatherband in Medium Rare and TNA Cat Amongst the Pigeons.
The only watch that I could identify so far is the one from Take-Over. It's definitely a Certina Watch.
Wrist watches
This is a special watch. It's saving Steed's life in TNA Faces.

It belonged to Steed oldest friend, Mark Clifford, who got killed in Faces.
His wife, Wendy, gave it to Steed after Mark's death, because she thought it was the watch of Mark's great grandfather and Steed should get it.
Actually it was the watch that Clifford got from his party, but nevertheless it saved Steed's live, as it stopped a 38 bullet, when his double tried to shoot him.
The Hunter from Dial a Deadly Number (below) is a legacy from his uncle. Mrs Boardman switched Steed's watch against an exact copy with an explosive device in it.
Another watch, a legacy from his grandfather appears in You'll Catch Yout Death.and Have Guns - Will Haggle
He wakes up the hypnotized Tara by using another pocket watch in Super Secret Cypher Snatch.
Mark's watch
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TNA Faces
Grandfather's watch in Have Guns - Will Haggle
The Hunter watch in Dial a Deadly Number
John Steed's Fashion