The expected credit loss (ECL) for a bond is calculated using the formula: $ECL = \text{Exposure at Default (EAD)} \times \text{Probability of Default (PD)} \times \text{Loss Given Default (LGD)}$ Where $LGD = 1 - \text{Recovery Rate}$.

For Bond A: $ECL_A = \text{£1,000,000} \times 4\% \times (1 - 70\%) = \text{£1,000,000} \times 0.04 \times 0.30 = \text{£12,000}$

For Bond B: $ECL_B = \text{£800,000} \times 6\% \times (1 - 60\%) = \text{£800,000} \times 0.06 \times 0.40 = \text{£19,200}$

The expected credit loss for the portfolio is simply the sum of the expected losses of the individual assets, as expected losses are strictly additive regardless of correlation: $\text{Total ECL} = ECL_A + ECL_B = \text{£12,000} + \text{£19,200} = \text{£31,200}$

Note that joint probability of default and default correlation are extraneous information used for calculating Unexpected Loss or Credit VaR, not Expected Loss.