The asset manager today (November 29) confirmed Mr Walker, who is already responsible for the management of a number of UK equity portfolios, would be appointed as co-head of UK equities on January 1.
According to Invesco the co-head model is already in place in several departments and Mr Barnett and Mr Walker had a “strong working relationship” and “common understanding” having worked together for 20 years.
Invesco added: “In recognising Mr Walker’s contribution to the business and formally recognising the mentoring role he has been informally doing, we are delighted that he has accepted this expanded role.
“Line management responsibilities for the team will be split between them [and they will] continue to run their current portfolio of funds with no changes.”
Mr Barnett, who was previously sole head of UK equities at the firm, has had a challenging year.
Mr Barnett’s Invesco Income fund has underperformed the IA UK All Companies Sector over the past five years, ranking 224 out of 228 over the five-year period he has been at the helm.
It has returned 8 per cent since 2014 compared with a sector average of 38 per cent.
Over the past three months the performance of the fund has improved, returning 5.7 per cent compared with its peers at 6.8 per cent.
His High Income fund tells a similar tale, also returning 8 per cent over the past five years (compared with a sector average of 38 per cent) but picking up over the past three months with a 6 per cent return, compared with the 6.8 per cent sector average.
The fund ranks 223 out of 228 for the past five-year period but 170 out of 257 for the three months just passed.
Mr Barnett has previously addressed the funds’ underperformance, telling investors it was “disappointing” and that he regretted some of the stock specific challenges, but that he backed his investment strategy to prove correct in time.
Darius McDermott, managing director at Chelsea Financial Services, said: "The UK team at Invesco have had a tough time since Mr Woodford's departure. The franchise has been in redemption and this has made it very difficult for them. Also they are value managers which had been out of favour.
"This has put considerable pressure on Mr Barnett who also took over as head of UK equities when Mr Woodford departed. This move to add Mr Walker as co-head makes sense to give Mr Barnett more time to concentrate on running the two big UK funds."
In 2014 Mr Barnett took over the funds from former star fund manager Neil Woodford.
Mr Woodford has hit the headlines over the past year after his flagship fund was suspended, triggering a domino of events which eventually led to his investment firm Woodford Investment Management announcing its closure.
Due to Mr Barnett’s similar investment style to that of his predecessor — both focus on UK facing and often smaller companies — a number of comparisons have been drawn between the two.
In October Morningstar downgraded Mr Barnett’s £6bn High Income and £2.8bn Income funds when its analysts cited concerns of style drift, increased exposure to mid- and small-cap companies, and “less attractive” liquidity.
But Mr Barnett hit back at the critics, claiming the liquidity in the portfolios remained strong and “very manageable”.
He noted the funds’ exposure to unquoted companies understandably drew attention after what happened with Woodford but stressed he had changed the way the funds invested in such stocks, reducing the total exposure to unquoted investments by half (around £1bn to £500m) in the five years since he took over the management role.
Last week FTAdviser reported Mr Barnett was the fund manager most hurt by the demise of WIM as investors pulled £648 from his two UK equity funds in Q3 of this year.
imogen.tew@ft.com
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