That looks like a gain of say 155K - (60K + 50K) = 45K. Knock off the AEA of 11.1K leaves say 34K liable to CGT at 18% or 28% or a combination of the two rates depending on your husband's income including the gain in the tax year of sale. Worst case scenario is an UK CGT tax bill of some 9.5k. There will a tax credit from France of 5.235K leaving some 4.3K of tax due to HMRC. This gain is declared on his self assessment tax return and for 15/16 tax year would be due by 31 January 2017.
I do hope that I have been of some assistance.
CGT calculation is:
155K - 120K = say 30K gain. CGT now comes out at around 7.6K as the current value is higher than in the previous estimate. Sorry for the delay; I went to bed early.. This ignores the AEA. However, the house was split between the 3 siblings so the 30K gain is divided by three to give 10K each. As the AEA is 11.1K there is no gain to tax so no CGT due. The French CGT gives no relief as there is no taxable gain under the UK regime.
I mislead you earlier failing to note the three way split. I do hope I have got it right this time.