Shares in Barclays jumped by 3.6% yesterday after it emerged that activist investor Bramson had bought a 5.16% stake in the bank through his Sherborne Investors vehicle.
At the end of February, Barclays was a top 10 holding in Jackson's £393 million fund, accounting for 2.1%. He did not disclose how big the position was following the latest transaction, which was funded by inflows into his portfolio.
Jackson (pictured) believes Bramson's unexpected move has increased the investment case for Barclays.
'Barclays was already a top 10 holding [in the fund] predicated on the fact it was an out of favour company in an out of favour sector 10 years on from the financial crisis,' Jackson told Wealth Manager.
'I thought the recent results were credible, although there is still lots of work to do. It is a complex business with many parts and Bramson will have an idea on how to improve these parts.'
Barclays released its results in February, showing a 10% increase in 2017 core profit to £3.5 billion.
However, this failed to drag Barclays back into the black with exceptional costs on the sale of its Africa division and tax changes causing a £1.9 billion loss.
Pre-tax profit was up from £3.2 billion in the prior year but remained well short of the £4.7 billion analysts had forecast. On a post-tax basis the business last year reported a £1.6 billion profit.
The bank has also promised to reinstate the dividend it cancelled two years ago.
While Bramson's recent success stories include F&C Asset Management and Electra, Barclays is by far his biggest project to date.
Jackson does not believe the challenge to turnaround Barclays is to large for the activist.
'Yes it is unusual to see an activist investor on the shareholder register of a large UK clearing bank but I don't think Barclays is too big for Bramson to shake-up,' the fund manager said.
'He [Bramson] has a good record of constructive engagement and I think UK companies are generally good at engaging with shareholders.
Jackson added: 'History would suggest that this is the time to buy rather than sell Barclays at this stage of the game.'
In the 12 months to the end of February he has performed well ahead of the peer group, returning 14.2% versus a sector average of 5.6%.