(ShareCast News) - Investors' faith in the heir designate at Barclays may not be misplaced, quite the contrary, but in the short-term his plans for a "strategic acceleration" means earnings may be even weaker, Investec said.That comes after the bank's valuation recovered to 1.0 times tangible net asset value (tNAV) for 2015 - an 18-month high.However, the possibility of double-digit rates of returns on equity (RoE) remains three years away, Investec analyst Ian Gordon wrote in a research note e-mailed to clients."Barclays' relatively weak capital (CET1 ratio 10.6% at Q1) restricts its options, and any acceleration of non-core run-off would likely be negative for tNAV," Gordon said.That came as he was already expecting tNAV to decline by five basis points in the second quarter of 2015.With investment bank revenues set to take a knock and after the Chancellor announced the imposition of a surcharge on bank profits it will be all the harder for Barclays to break out of single-digit RoEs in the short-term, Gordon added.The analyst downgraded the bank's shares to 'sell' from 'hold' and lowered its price target on the stock to 265p from 270p.