The match is being played after Cornwall’s County Championship final against Lancashire (12noon).
Former Plymouth College pupil Slade will start at centre, with Cowan-Dickie lining up at hooker.
Both players will be hoping to push their claims for World Cup places. Cowan-Dickie’s chances of making the final party have improved after Dylan Hartley was withdrawn from the training squad due to a suspension that will not end until after the first World Cup game.
England head coach Stuart Lancaster said: “We’ve had a short but very good week in camp and the players have worked hard. I’ve been extremely happy with the way they have gone about their training and prep off the field.
“This is an exciting group of players who will be eager to impress in an England shirt with a number of guys having one eye on the World Cup in September.
“We know the Barbarians have a large number of experienced international guys and they will be ready for us having played Ireland last night. We are expecting a tough encounter.”
ENGLAND TEAM TO FACE BARBARIANS
15 Mathew Tait (Leicester Tigers)
14 Christian Wade (Wasps)
13 Elliot Daly (Wasps)
12 Henry Slade (Exeter Chiefs)
11 Marland Yarde Harlequins)
10 Danny Cipriani (Sale Sharks)
9 Lee Dickson (Northampton Saints, captain)
1 Matt Mullan (Wasps)
2 Luke Cowan-Dickie (Exeter Chiefs)
3 Kieran Brookes (Newcastle Falcons)
4 Ed Slater (Leicester Tigers)
5 Joe Launchbury (Wasps)
6 Mark Wilson (Newcastle Falcons)
7 Jack Clifford (Harlequins)
8 Josh Beaumont (Sale Sharks)
16 Tommy Taylor (Sale Sharks)
17 Alex Waller (Northampton Saints)
18 Gareth Denman (Northampton Saints)
19 James Gaskell (Wasps)
20 Jon Fisher (Northampton Saints)
21 Will Chudley (Exeter Chiefs)
22 Shane Geraghty (London Irish)
23 Alex Lewington (London Irish)