It depends whether or not the item of expenditure has been allowed for within the budget for the year. To quote the current model financial regs:
4.1. Expenditure on revenue items may be authorised up to the amounts included for that class of expenditure in the approved budget. This authority is to be determined by:
· the council for all items over [£5,000];
· a duly delegated committee of the council for items over [£500]; or
· the Clerk, in conjunction with Chairman of Council or Chairman of the appropriate committee, for any items below [£500].
A gift to the local history society might be a legitimate item of expenditure under Section 137, if you have a budget for this. The limit of £500 can only be exceeded by a resolution of the council. As a councillor myself, I would want to know why it was necessary for this matter to be handled in this way, but I would have no authority to overrule the decision.
The emergency power has already been explained. The other relevant powers include the authority for the Clerk to make payments between meetings if necessary to avoid the payment of interest (para 5.5) and to make regular payments previously authorised as part of an ongoing payments schedule (para 5.6).
It is important to note that these powers are given to the Clerk/RFO, not the Chair, who has no such powers unless a specific provision has been agreed in the setting of the budget.