Originally, this hook was not made for fly-fishing but for Texas Rigs. However, it works really well for fly-fishing in waters with a lot of weed or if you want to fish close to the bottom without getting too many unintended hook ups. Black Nickel Finish Available in size 1/0, 3/0 & 5/0...
IMHO it also depends on the style of fly you want to tie: long shank Aberdeen-style hooks give a greater ability to build up a body, and/or build up a stacked/staggered wing along the back.
Shorter-shanked hooks rely more on quite carefully stacked and tied material in a long, trailing, wing; most of the hook shank is needed for the tying in, and the head and eyes.
I have not found any modern hooks to be deficient in holding power: sea fish (and sea fishing) tends to be a harder task master, hence I find the Cox & Rawle hooks work well for pike. Just avoid the very fine Aberdeens: these are for flatties only!
I see you are in Dorset.
If you visit West Bay, the big (sea) tackle shop there has a fabulous selection of hooks, many of which (especially the Sakuma 470s) are fabulous for tying flies, both pike and saltwater. And at prices about one third the price of premium saltwater hooks for fly tying (e.g. Gamakatsu etc).
sakuma manta are superb hooks, look at sea fishing hooks and avoid the fly brands and you will save a fortune and get a similar or better product. I am good friends with two very well known pike fly tyers and both use sea fishing hooks for their flies, sakuma, mustad and cox & rawle, both supply flies to the top comp pike fishers from the UK and Europe and the musky guys in the USA/Canada.
I've used Wizard and Fly fishing dept, both from Bogdan Gawlik for big pike, tied 4/0 - 6/0, every bit as good as Fulling Mill, and other pike specialist pike hooks but much cheaper. Wizard in particular have a nice wide gape, albeit they look a bit square, and haven't let me down.
As above, Cox and Rawle have patterns that are suitable, I agree that if you've a decent sea angling shop take a look at what they have, you can buy in 25's usually and they are much cheaper. Heavy duty Aberdeens are fine for canal pike, or any waters where 20s are very rare, and cost pennies tied as tandems on 2/0's. The only sea hooks I stay away from are the heavier stainless types, too heavy in the wire and the points aren't as sharp as a result, usually big barbs too (although I tie many bass flies on these in 1's)