A disastrous first quarter of an hour cost West dear in their fight to get out of the North One East relegation zone.
It began as early as the second minute after a charging run up the left by Liam Checksfield resulted in a penalty for the visitors inside the home 22.
West opted for the lineout only to lose the ball at the tail.
When the same thing happened a minute later, Alnwick’s speedy back spun the ball out wide where winger Jonny Burn raced home from inside his own half.
He was involved in a break again two minutes later, after taking a kick on the edge of his own 22, with full back Jack Smales finishing off with a 50 metre run to the posts.
Alnwick centre Rob Cuthbert then threw off several tackles as he burst into the 22 to force his way over - goalkicker James Bird taking the score to 21-0 with just 15 minutes on the clock.
West were facing a hiding from a side which had had to reshuffle its pack with regular full back Bird pressed into service at No.8 where he looked more than comfortable.
Fortunately for the Brinkburn side, they continued to have the better share of territory, stepped up their tackling and got back into the game when a sharp moved in the home 22 saw a floated pass destined to send Will Hildicth in at the corner.
However, full back Smales got there first with a deliberate knock on. He went to the sin-bin with West celebrating their first penalty try in a season where there is no requirement to take the conversion.
With Alnwick down to 14, Ryan Painter tried his luck with a kick and chase down the touchlinewhich almost paid off. However the pressure stayed on and Hildicth did get his try wide on the left as the home defence was stretched.
Gavin Painter added the extras and at 21-14 West were giving as good as they got.
However, problems at the breakdown led to a succession of long-range penalties allowing Bird to convert three before the break to allow his side to turn round 30-14 to the good.
Gavin Painter added his own long-range penalty after the break only to see Alnwick go for a line-out instead of taking their own shot at the posts.
It paid off with flanker Nick Richardson touching down as his pack drove him over.
Bird’s impeccable right boot provided the extras and he was on target again from out wide after Alnwick scored the try of the game.
It began up the right wing through Peter Moralee with a succession of players taking the ball on, offloading in contact and eventually stretching the West defence to allow Burn an easy run in the left hand corner.
That proved to be a fitting to the Alnwick scoring and with 15 minutes left West set about salvaging some pride.
It was the front row which came up with the goods. First Alex Key peeled off from a maul to go over, and then Andrew Rollins finished off some excellent support play by crashing over between the posts to give West a deserved try bonus point.
West skipper Carl Miller said there were positives, but admitted the poor start gave his side too much to do.
“We never gave in,” he said. “Alnwick had some real pace in the backs and we were made to pay for some poor first up tackling.
“Then when we got back in the game we gave away far too many penalties. We did get a bonus point and the actual try count against a side up at the top of the league was 5-4.”
West now have a week off before facing fellow strugglers Dinnington at Brinkburn.
Alnwick: Jack Smales, Peter Moralee, Rob Cuthbert, Ali Gray, Jonny Burn, James Warcup, Simon Ord, Duncan Smith, Harry Sordy, Pete Brown, George Fox, Matty Gray, Gordon Smith, Nick Roichardson, James Bird.
Reps (all used) : John McLaughlin, Ropry Mallaburn, Ben Courty.
Tries: Burn (2), Smales, Cuthbert, Richardson.
Cons: Bird (5)
Penalties: Bird (3)
West: Will Hilditch, Liam Checksfield, Peter Youll, Gavin Painter, Adam Peacock, Zac Southern, Ryan Painter, Andrew Rollins, Jordan Foulds, Alex Key, Jake Linighan, Joe Rafferty, Carl Miller( captain), Scott Butcher, Andy Turner.
Reps (all used); Adam Brown, Craig Hadwen, Ben Armstrong.
Tries: Hilditch, Key, Rollins, Penalty try.
Cons: G Painter (3)
Pen: G Painter (1)
Referee: Ollie Wickes (Surrey)