The main risk in accepting the standard undertaking is that the seller’s solicitor may fail or be unable to keep the promise. That will then put the buyer’s solicitor in breach of duty to his own client, especially where the buyer’s solicitor failed to ensure that the seller was authorised to receive the completion moneys as agent for the lender. If that agency does exist, then receipt of completion moneys by the seller’s solicitor is equivalent to receipt by the lender (even if the money does not actually reach the lender). 



From the perspective of the buyer’s solicitor, there are suggestions for additions or alternatives to the usual undertakings in the Commercial Property Standard Enquiries: 


• send part of the purchase price (ie the amount needed to discharge the mortgage) directly to the lender;

• request sight of confirmation from the lender that the seller’s solicitor has been appointed the lender’s agent for the receipt of the redemption money. Note that confirmation from the seller’s solicitor will not be sufficient (despite what is said in the Code for Completion by Post);

• if the amount of mortgage debt is more than the minimum indemnity insurance cover, then only accept an undertaking for the DS1 or DS3 if you also get a warranty from the seller’s solicitor that it has insurance cover exceeding the amount required to redeem the mortgage. Indeed, many firms do this whenever there is a transaction exceeding the value of the minimum level. 



The ultimate protection, of course, is simply to refuse to accept an undertaking from the seller’s solicitor. But, if you want to do that, it will be necessary to put a special condition in the contract to that effect.